HTML, DHTML and Java Script

HTML, DHTML & JavaScript

HTML, DHTML & JavaScript PRAVESH – Student Guide Subject: HTML. DHTML & JavaScript

V1.0

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Chapter 1: Introduction to Web and Internet...................................................................................3 Chapter 2: HTML's Role on the Web...........................................................................................13 Chapter 3: Creating a Web Page and Entering Text ....................................................................24 Chapter 4: Changing and Customizing HTML Text....................................................................33 Chapter 5: Displaying Text in Lists .............................................................................................43 Chapter 6: Adding Graphics to Your Web Pages.........................................................................54 Chapter 7: Hypertext and Creating Links.....................................................................................64 Chapter 8: Clickable Image Maps and Graphical interfaces........................................................74 Chapter 9: HTML Forms..............................................................................................................85 Chapter 10: Images, Multimedia Objects and Background Graphics ..........................................96 Chapter 11: Adding Tables to your Documents.........................................................................102 Chapter 12: Frames ....................................................................................................................110 Chapter 13: Introduction to DHTML .........................................................................................122 Chapter 14: Introduction to CSS ................................................................................................127 Chapter 15: Introduction to JavaScript........................................................................................169 Chapter 16: JavaScript Syntax ....................................................................................................174 Chapter 17: Basic Programming Constructs ...............................................................................185 Chapter 18: Objects, Events & Document Object Model ...........................................................200 Chapter 19: Alerts, Prompts & Confirms....................................................................................216 Chapter 20: Form Validation.......................................................................................................223 Chapter 21: Mouse Over Effects .................................................................................................232 Chapter 22: Pop-Up Windows ....................................................................................................244 Chapter 23: Cookies ....................................................................................................................255 Chapter 24: Document Object Model .........................................................................................264

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HTML, DHTML & JavaScript Chapter 1: Introduction to Web and Internet

Objectives • • •

Explain Introduction of WWW Understand Client/Server Architecture Explain Internet Concepts

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Introduction to Web The web is a complex, international, cross platform, cross language, cross cultural mesh of servers, clients, users, databases, and quite a few artificial intelligences all talking, working, searching, viewing, accessing, downloading together. Tim Berners-Lee, a computer specialist from the European Particle Physics Laboratory (CERN) in 1989, initially created the web. It is the largest client/server system implemented to date. A client/server system is a very keen way of distributing information across information systems like a local area network (LAN), a wide area network (WAN), or the Internet.

Working of client – server Architecture A client/server system works like this: A computer (called a server) sits in some office somewhere with a bunch of files that people might want access to. This computer runs a software package that listens to requests over the networks i.e. LAN (Local Area Network) or WAN (Wide Area Network). The "server software" will then access the server hardware, finds the requested file, send it back over the wires to the "client" who requested it, and then wait for another request from the same or another client. The "client" is actually a software program, like Netscape Navigator, that is being operated by a person who is the one who really wants to see the file. Process will look as follow:

Protocol use for communication in between client and server is HTTP (HyperText Transfer Protocol). HTTP is a "request-response" type protocol that specifies that a client will open a connection to a server then send a request using a very specific format. The server will then respond and closes the connection. These requests will be in some language and some format that the computer understands normally HTML (Hyper Text Markup Language). Upon Request of client (Web browser) server send a response (Web page), actually the web browser will display a document exactly the way it receives it from the web server. For example, if the document requested is an image, the web browser will display it directly. However, if the document is an HTML document, the web browser will "interpret" the HTML and display it according to the instructions contained within the HTML code. HTML (Hyper Text Markup Language) is a very simple language used to "describe" the logical structure of a document. Though HTML is often called a programming language it is really not. In HTML itself, there is no programming-just the "marking up" of regular text for emphasis and organization. Programming languages can be used to compute something such as the square root of pi or some other such task. Typically programming languages use conditional branches and loops and operate on data contained in Training & Development Division

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abstract data structures. HTML is much easier than all of that. HTML is simply a 'markup language' used to define a logical structure rather than compute anything.

The World Wide Web and Web Servers Probably the most important thing to remember about the World Wide Web and the Internet in general is that they are global in scale and often a very cooperative venture. Information on the Web tends to be distributed around the world, and it's just as easy for you to access a site in New Zealand or Japan as it is to access Web information in your own state. The basic reason for learning HTML is to create pages for the World Wide Web. Before you start, though, you'll want to know a little about how this whole process works. We'll begin by taking a look at Web browsing programs, then we'll talk about how the World Wide Web works, and we'll discuss some of the terms associated with surfing the Web. Finally, we'll round out the discussion by talking about the Internet in general and the different services available on the Internet and how they interact with the Web.

World Wide Web The World Wide Web is an Internet service, based on a common set of protocols, which allows a particularly configured server computer to distribute documents across the Internet in a standard way. This Web standard allows programs on many different computer platforms (such as UNIX, Windows 95, and the Mac OS) to properly format and display the information served. These programs are called Web browsers. The Web is fairly unique among Internet services (which include Internet e-mail, Gopher, and FTP) in that its protocols allow for the Web server to send information of many different types ,

Here's a Gopher site as displayed through Netscape Navigator (text, sound, graphics), as well as offer access to those other Internet services. Most Web browsers are just as capable of displaying UseNet newsgroup messages and Gopher sites as they are able to display Web pages written in HTML

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The Web Page The World Wide Web is composed of millions of Web pages, each of which is served to a browser (when requested) one page at a time. A Web page is generally a single HTML document, which might include text, graphics, sound files, and hypertext links. Each HTML document you create is a single Web page, regardless of the length of the document or the amount of information included.

The Web Site A Web site, then, is a collection of Web pages under the control of a particular person or group. Generally, a Web site offers a certain amount of organization of its internal information. One might start with an index or default page for a Web site, and then use hypertext links to access more detailed information. Another page within the Web site may offer links to other interesting sites on the Web, information about the organization, or just about anything else. Web site organization is an important consideration for any HTML designer, including those designing and building corporate Web sites. The typical corporate Web site needs to offer a number of different types of information, each of which might merit its own Web page or pages. Hypermedia: Text and Graphics on the Web With graphical browsers such as NCSA Mosaic and Netscape Navigator, the hypertext concept of the Web was introduced to the world of multimedia, resulting in the hypermedia links that are possible in HTML. Now, this really isn't much different from the hypertext links we talked about in the previous sectionthe only difference is that hypermedia links point to files other than HTML documents. For instance, a hypermedia link might point to an audio file, a QuickTime movie file, or a graphic file such as a GIF- or JPEG-format graphic. Because of the flexibility of the Web protocol, a Web server can send these files just as easily as can an HTML document. All you need to do is create the link to a multimedia file. When users click that link, the multimedia file will be sent over the Web to their browser programs. Helper Applications Once the user’s Web browser receives the multimedia file, it's up to the browser to decide how to display or use that multimedia file. Some browsers have certain abilities built in-especially the basics, such as displaying graphics files or plain ASCII text files. At other times, browsers will employ the services of a helper application

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Example of Web browser helper applications

Most of these helper applications will be add-on programs that are available as commercial or shareware applications. The browser will generally need to be configured to recognize particular types of multimedia files, which, in turn, will cause the browser to load the appropriate helper application. Once loaded, the downloaded multimedia file will be fed to the helper applications, which can then play or display the multimedia file Common Multimedia Formats Although it seems that multimedia formats are constantly being added and improved for the Web, some of the more common types of multimedia files are listed in Table 1.1 with their associated file extensions. This list isn't exhaustive, but it should give you an idea of the types of files that can be distributed on the Web. File Format

Type of File

Extension

Sun Systems sound

audio

.au

Windows sound

audio

.wav

Audio Interchange

audio

.aiff, .aifc

MPEG audio

audio

.mpg, .mpeg

SoundBlaster VOiCe

audio

.voc

RealAudio

audio

.ra, .ram

CompuServe GIF

graphics

.gif

JPEG (compressed)

graphics

.jpg, .jpeg

TIFF

graphics

.tif, .tiff

Windows Bitmap

graphics

.bmp

Apple Picture

graphics

.pict

Fractal Animations

animation

.fli, .flc

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VRML

3D world animation

.wrl

MPEG video

video

.mpg, .mpeg

QuickTime

video

.mov, .moov, .qt

Video For Windows

video

.avi

Macromedia Shockwave

multimedia presentation

.dcr

ASCII text

plain text

.txt, .text

Postscript

formatted text

.ps

Adobe Acrobat

formatted text

.pdf

Multimedia Formats Common to the Web Not all of these different file formats necessarily require a special helper application. Many sound helpers will play the majority of different sound files, for instance, and some graphics programs can handle multiple file types. For the most part, you will need different helper applications for the various video, animations, and formatted text file types.

Internet Services and Addresses Aside from being hypertext-based and capable of transferring a number of multimedia file formats, the Web is unique in its ability to access other Internet services. Being the youngest of the Internet services, the Web can access all of its older siblings, including Internet e-mail, UseNet newsgroups, Gopher servers, and FTP servers. Before we can access these services, though, we need to know what they do and how their addressing schemes work. Internet E-mail Internet e-mail is designed for the transmission of ASCII text messages from one Internet user to another, specified user. Like mail delivered by the U.S. Post Office, Internet e-mail allows you to address your messages to a particular person. When sent, it eventually arrives in that person's e-mail box (generally an Internet-connected computer where he or she has an account) and your recipient can read, forward, or reply to the message. Internet e-mail addresses follow a certain convention, as follows: [email protected] domain where username is the name of the account with the computer, host is the name of the computer that provides the Internet account, sub-domain is an optional internal designation, domain is the name assigned to the host organization's Internet presence, and first-level domain is the two- or three-letter code that identifies the type of organization that controls the host computer. An example of a simple e-mail address (mine) is [email protected], where tstauffer is the username, aol is the domain, and com is the first-level-domain. com is the three-letter code representing a commercial entity. First-level domain

Organization Type

.com

Commercial

.edu

Educational

.org

Organization/Association

.net

Computer Network

.gov

Government

.mil

Military Installation

.ca

Canadian

.fr

French

.au

Austrailian

.uk

United Kingdom

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.jp

Japanese Common First-Level Domain Names

You may have also noticed that the address doesn't include a host name or a sub-domain. For this particular address, it is unnecessary because America Online handles all incoming Internet e-mail through a gateway. Once it receives the e-mail, it may indeed send it to another computer within its online service, but this is an internal operation that doesn't require a specified host in the Internet address. Consider [email protected]. Notice how it uses all of the possible parts of an Internet address. todd is the username, lechery is a host computer (in this case, an actual, physical computer named "lechery"), isc is a sub-domain name that represents the computers in the Institute for Scientific Computation, tamu is the domain name for all Internet-connected computers at Texas A&M University, and edu is the three-letter code for educational, which is the type of organization that Texas A&M is considered to be on the Internet.

UseNet Newsgroups The next Internet service we'll talk about is UseNet newsgroups. These are the discussion groups on the Internet, where people gather to post messages and replies on thousands of topics ranging from computing to popular entertainers, sports, dating, politics, and classified advertising. UseNet is a very popular Internet service, and most Web browsers have some built-in ability to read UseNet discussion groups. Like Internet e-mail, UseNet discussion groups have their own system of organization to help you find things. This system uses ideas and syntax that are similar to e-mail addresses, but you'll notice that UseNet doesn't require that you find specific hosts and servers on the Internet-just a particular group. UseNet newsgroup names use the following format: first-level name.second-level.third.forth... The first-level name indicates the type of UseNet group this is, the second narrows the subject a bit, and the address continues on until it more or less completely describes the group. For instance, the following are both examples of UseNet newsgroup addresses: co.general comp.sys.ibm.pc.misc The first-level name co means this is a local UseNet group for the Colorado area, and general shows that it's for discussion of general topics. Comp is a common first-level name that suggests this is an internationally available newsgroup about some sort of computing issue (see Table). The other levels of the name tell you more about the group. First-Level Name

Description

alt

Alternative groups

biz

Business issues

clari

Clarinet news stories

comp

Computing topics

misc

Other general discussions

news

General news and help about UseNet

rec

Recreational topics

sci

Scientific discussions

soc

Social issues

talk

Debate-oriented groups Common UseNet First-Level Newsgroup Names

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Gopher and WAIS Gopher has been described as the poor man's Web, and it's definitely true that Gopher is a precursor to some of the Web's capabilities. Gopher is a system of menu items that link sites around the world for the purpose of information retrieval. This isn't a hypertext system like the Web, but it is similar to the Web in that it's designed for document retrieval. While Gopher can only offer access to text files and allows you to download files using the FTP protocol, it is still used occasionally by academic, government, and similar sites. Fortunately, your Web browser can easily offer Gopher access too, so there's no need to have a separate application. WAIS, or Wide Area Information Servers, are basically database servers that allow you to search databases that are attached to Gopher menus. Library databases, academic phonebooks, and similar information are kept in WAIS systems. Gopher and WAIS both generally require that you have the exact address of the Gopher server available to you. These addresses are in the following form: host.sub-domain.domain.first-level domain This works essentially like an e-mail address without a username. All the Gopher application needs to know is the exact Internet location of the Gopher server computer you'd like to talk to. An example might be marvel.loc.gov. This takes you to a Gopher menu for the Library of Congress.

FTP The File Transfer Protocol (FTP) is the Internet service that allows computers to transfer binary files (programs and documents) across the Internet. This is the uploading/downloading protocol that you might use to obtain copies of shareware or freeware programs, or that might be useful for downloading new software drivers from a particular computer hardware company. Using a model identical to the Gopher system, FTP addresses use the following format: host.sub-domain.domain.first-level domain Like Gopher addresses, an FTP address is simply the Internet address of a particular host computer. In fact, the same host address can be used to serve you both Gopher documents and FTP file directories, based on the type of protocol your access software requests. The following example is the FTP address for downloading support and driver files for Apple Macintosh computers and Apple-created Mac and Windows software: ftp.support.apple.com In most cases, FTP connections also require some sort of login procedure, which means you'll need a username and password from the system administrator to gain access. The majority of public FTP sites, however, are anonymous sites, which allow anyone access to their files. For these sites, the username is generally anonymous, and you're asked to enter your e-mail address for the system's password.

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Review Questions 1. What does URL stand for? a. United Route Link b. Uniform Resource Locator c. Up Real Late d. Unknown Redirection Link 2. What is a. b. c. d.

the name of the language you use to write a web page? HTTP UML HTML URL

3. Which of the following terms is a "browser"? a. World Wide Web b. Netscape c. Launcher d. E-Mail 4. All web addresses start with which of the following? a. ftp b. http:/ c. http:// d. www 5. A word a. b. c. d.

that looks underlined on a web page is usually what? an important word the web address a "link" to another or same web page Nothing special

6. Which description does NOT apply to the Internet? a. an interconnected system of networks that allows for communication through e-mail, LISTSERVS, and the World Wide Web b. a public network neither owned nor run by any one group or individual c. a vast network that connects millions of computers around the world d. a catalogue of information organized and fact-checked by a governing body 7. http://www.lntinfotech.com is an example of what? a. a URL b. an access code c. a directory d. a Server

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Summary Web is a complex, international level, cross platform, cross language, cross cultural mesh of servers, clients, users and databases. The World Wide Web is an Internet service, which allows a particularly configured server computer to distribute documents across the Internet. HTTP is used between client and server communication so that communication can happen smoothly and properly. Internet e-mail is designed for the transmission of ASCII text messages from one Internet user to another. Newsgroups are the discussion groups on the Internet, where people gather to post messages and replies on thousands of topics ranging from computing to popular entertainers, sports, dating, politics, and classified advertising. Gopher is a system of menu items that link sites around the world for the purpose of information retrieval. Using File Transfer Protocol (FTP), the transfer of binary files (programs and documents) across the Internet is happening.

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HTML, DHTML & JavaScript Chapter 2: HTML's Role on the Web

Objectives • • • • •

To explain Advantages and Disadvantages of Web Understanding Current state of HTML Understand what is web Server Speed of web server, ISP for web sites Discuss uploading of pages on web server

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Another emerging use for HTML on the Web is as a basis for something called a Web application. In essence, a Web application is a Web site designed to do more than simply present pages and hypermedia links to its users-it actually acts as a front end for data processing. Once the data are entered on the page, the Web server passes them to programs that process the information looking up the product in the database or taking the order. The results of these programs can be generated complete with HTML codes, so that the answers can be viewed by the salesperson in her Web browser.

Advantages and Disadvantages of the Web Most small or large businesses have a compelling reason to create a presence on the World Wide Web. It's an important new medium for communication that is relatively inexpensive to implement, it's a boon for dealing with customer service issues, and it's gaining popularity in leaps and bounds. But any good HTML designer should realize that there are also certain disadvantages to the Web. Advantages There are many good reasons to commit to creating a presence on the World Wide Web. Most of these are geared toward businesses, but you'll notice that these advantages are available to any Web site: Multimedia presentation-A Web site allows you to do things that are simply not possible in any other medium. With some of the visual impact of television, the informational utility of print, and the personal appeal of radio, the Web is an effective tool for taking marketing information to another level. Products can be explained and offered in depth, along with pictures, video, sound, and even animation. Interactivity-There are a number of different areas where the fact that your user can interactively determine what to view or hear can really make the difference for a business. Especially important is the added value the Web gives you for customer service, technical or product support, and immediate feedback. While most of any Web site is automated, it gives you an opportunity to answer frequently asked questions and point customers to resources that may help them solve problems on their own. While this may seem like an advantage reserved for computer companies, consider the implications for service-oriented industries like travel, consulting, catalogue sales, and business-to-business sales. Flexibility-If your business relies on printing or publishing as a medium, you may immediately see the advantage of the Web. Changes on the Web are relatively instantaneous, and the speed with which an update can be made is measured in minutes, not weeks. Consider the financial planner's or real estate agent's sales newsletter. Instant changes on the World Wide Web give their Net-savvy clients a timebased edge. Incorporating the Web into the services you offer a client gives you an added value in their eyes, especially in time-sensitive industries. Easy High-Tech-Whether you're a small or large business, it's important to keep up with technology in order to satisfy customers and be up on the "latest." Web pages are moving toward a point where they'll be expected of large businesses and not unusual from small ones. Like e-mail a couple years ago, and fax machines before that, it's become important to keep up with the Web. Fortunately, it's also rather easy to get started with HTML and quickly develop a Web site. Disadvantages It's difficult to say that there are disadvantages in having a Web site, since most people and companies will use a Web site to enhance their marketing and customer service efforts, not supplant them. That said, there are a few hurdles to leap, and they should definitely be considered before your Web project takes off: Learning Curve- It will take a while for folks to learn HTML, figure out how to upload pages, create appropriate graphics, and design effective Web sites. You'll also need to find an effective and helpful Internet service provider (or a similar in-house IS employee at a larger corporation) who can help you get online. Appearance- To be truly effective, a Web site also needs to be attractive and easy to use. For many companies, especially larger ones, that will mean using professional artists, writers, and designers. Training & Development Division

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Beginning this task can be daunting, and will require a reasonable budget-which may be intimidating when management isn't sure what the benefits will be. Maintenance and Timeliness- One of the worst things that can happen to a Web site is for it to sit dormant for weeks or months because it's the pet project of an interested employee who has less time for it than she originally anticipated, or because every change to the Web site must first be approved by a committee. It's important that a Web developer be relatively free to spend time on the project, and that someone be available to make timely decisions. Without this, the Web site loses some of its inherent advantages. Security- Transmitting data via Internet technology, including the Web, is inherently a rather unsecured process. For data to be transmitted over the Web, it has to pass through a number of different servers and hosts-and any of the information you offer could potentially be read or held by any of these people. This has been a strong argument against commerce on the Web, as people recognize the dangers in revealing personal information (for instance, credit card numbers). Currently, it's difficult to create completely secure Web sites that offer access only to password-bearing users, and those passwords are often not impossible to intercept. Copyright Issues- The lack of security holds true for the Web designer-nearly anything you create on the Web can easily be read or copied by anyone with Web access. This is intimidating both to artists and publishers who want to make sure that Internet access doesn't, in some way, devalue their published (and profitable) efforts. Cost-Depending on the size of your organization and the expertise of its people, a Web site can quickly become expensive. Learning HTML and creating a reasonable site isn't that difficult (as you'll see in this book), but maintaining the appropriate equipment, paying the dedicated staffers, and bringing in consultants, designers, programmers, and IS technicians as the site grows can quickly expand the budget. The advantages will often outweigh these costs, but any Web developer should be aware that Web sites tend to get bigger and more time-consuming as time goes on.

Secure Connections on the Internet Some Web server software packages offer an implementation of the Secure Sockets Layer (SSL), a protocol that sits "on top" of TCP/IP (the Internet networking protocol) and "below" HTTP. Its purpose is to secure the transmission of HTTP data over the Web. With an SSL server (usually noted by its https://-protocol URL) and an SSL-capable browser program, transmissions over the Web are encrypted in such a way that users trying to read the data as they pass over the Internet are treated to nothing but garbled text. SSL is a feature of, among others, the Netscape Enterprise Server, which is designed to allow users to access a Web site in a secure fashion so that credit cards and other personal information can be passed with relative assurance. Although this is not directly relevant to HTML designers, if you have the opportunity to create a commercial Web site (or otherwise ask for personal information from users), you might look into the possibility of using an SSL-based secure Web server to offer your users peace of mind. And, while SSL isn't the only security scheme, it's the most widely supported.

The Current State of HTML With these commercial demands, however, have come different solutions. For every extension Netscape adds to HTML, there is generally (eventually) a standard agreed to by the World Wide Web Consortium (W3C) that meets the same need. Unfortunately, the implementation isn't always the same. So, it's possible for an HTML 4.0 level standard, for instance, to provide for exactly the same layout functions as Netscape-but do it in a way that isn't compatible with Netscape's browser. So HTML is currently in a bit of a flux. The best you can hope for is that the HTML standard is agreed upon and maintained more quickly in the future as more ideas pop up. At the same time, it's important that the standard remain well thought-out, and that it isn't allowed to become bloated and unworkable. In fact, this is probably the justification for recent changes to the standard's bodies. With the W3C taking control of HTML, it suggests a shift in the ultimate power over HTML to the corporate players. From now on, you can probably assume that HTML extensions beyond what is generally considered HTML 3.0 will become standard on a case-by-case basis. Overall, this is probably a good thing, since Training & Development Division

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standards can be agreed on as technology emerges-and competing browsers can all use the same methods to incorporate new technology.

What You Need for a Web Site Although creating HTML pages is easily the most time-consuming part of building your Web site, another equally important part is figuring out how you're going to get those pages on the Web. You'll need Web server software, an Internet connection, a Web URL for your pages, and a system for organizing your pages and graphics. Depending on how you gain access and how complicated your site is, just getting your first page up on the Web can take a certain amount of planning.

Web Server Before you can display your HTML pages on the Web, you'll need access to a Web server. This may already be taken care of for you, especially if you work with an Information Systems (IS) department in a larger corporation. If this is the case, you'll just need to know how and where to send your HTML files when you want to update the site. Otherwise, you'll need to make some arrangements on your own. It isn't terribly difficult to set up your own Web server-especially if you already have a high-speed connection to the Internet. If you access the Internet through an Internet service provider (ISP), you'll want to discuss this with them, though. More than likely, they're willing to provide you with space on their Web server computers. If your Web site is a fairly small venture, or if you're not ready for a heavy investment in equipment, then using your ISP's Web server is a great (and very common) alternative.

What is a Web Server? In its essence, it's the job of a Web server to accept connections from Web browsers all over the Internet and, when requested, send them the HTML documents that are available from your site. A Web server is simply a computer with an Internet connection that runs software designed to send out HTML pages and other file formats (such as multimedia files) (see below fig.). The server computer should have a relatively high-speed connection to the Internet (faster than any available modem connections, for instance) and be powerful enough to deal with a number of simultaneous connections from the Internet.

WebSTAR Web server software running on a Macintosh computer

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Web server software generally requires a fairly robust operating system (like UNIX, Windows NT, or OS/2), although software is available for other versions of Microsoft Windows, and the Macintosh OS is a very popular choice for Web server computers. The software you use depends on your level of experience with Internet connections and various operating systems.

Speed of the Server The other major consideration is how popular your Web site will be. The more hits, or connections, your Web server receives at one time, the more powerful the computer should be-and the faster your connection to the Internet. Most Internet connections are measured in terms of bits per second (bps), which translates loosely as "how many bits of data can be transmitted across the Internet in a second." In computer, it takes eight bits to make up one byte of computer information-and a byte is what is required to create a character of text. The typical modem connection is 14,400 bps, which translates to roughly 1,800 characters (bytes) transferred every second. If a typical page of text contains 300 words then, and each word averages six characters per word, this connection would yield roughly a page-per-second transmission rate. A 25kilobyte (KB) file (such as a very small GIF file) would take about 14 seconds to transmit over this connection. This doesn't sound terribly slow, until you start to take into account the idea that more than one connection might occur with the Web server. If ten people connect to our server over this connection, it will take ten seconds to complete the task of sending each of them a single page of data. If that page totaled 25 KB in size (that is, if it included graphics and other elements), it could take over 140 seconds to complete that same task. These transmission rate numbers all reflect ideal conditions. In real life, phone line noise, traffic on the Internet, and other factors will slow down transmission rates. Throughput on a 14,400 bps connection is often somewhere between 1,100 and 1,300 characters per second. If the typical well-designed Web page is between 30 KB and 50 KB in size, you can see that we're going to start running into problems with this type of connection. There's the potential for someone to wait a number of minutes between the transfers of each page they request on your Web site. If the average commercial break on television is three minutes, just think how annoyed your users are going to get.

Types of Internet Connections So your server will need a faster connection. If Internet access is available to you through your company's Local Area Network (LAN), you probably already have a high-speed connection. Ask around your IS department. If you're running a small business or home office, you won't have to worry about high speed if you make your Web pages available on your ISP's Web server. If you're going to use your own Web server computer, though, you'll need a high-speed Internet connection that you can connect to that computer. Details some of the possible connections. Connection Speed

Connection Technology

14.4/28.8 Kbps

High-speed modem

56 Kbps

56K leased line

64 Kbps

Single-B-Channel ISDN

128 Kbps

Basic Rate ISDN

up to 1.5 Mbps

Primary Rate ISDN (U.S.)

1.5 Mbps

T-1 dedicated line

45 Mbps

T-3 dedicated line Internet Connection Speeds and Technologies

The minimum for an acceptable Web server connection is probably a basic-rate ISDN (Integrated Services Digital Network) connection, which offers 128,000 bps connections to the Internet. ISDN technology uses your existing phone wiring to provide an enhanced, digital, telephone connection. Training & Development Division

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Using a special network adapter card for your computer, you can use the ISDN line to dial an appropriately equipped ISP. You can also use the ISDN connection for regular telephone calls. A T-1 line is the typical connection for an ISP or a large business, and these lines generally cost thousands of dollars per month for Internet access, as do primary-rate ISDN connections. T-3 lines currently serve as the backbone of the Internet, and are generally only found connecting university, government, and supercomputing organizations.

Dealing with an ISP For any sort of connection to the Internet, you'll probably need to deal with an Internet service provider. These companies offer dial-up and special high-speed connections to the Internet, as well as generally offering Web and other types of Internet servers for your use. For the typical smaller Web site, you'll want to buy space on the ISP's Web site. Generally this will give you an URL that begins with the name of the ISP's host computer, but points to a special directory for your HTML pages, such as http://www.isp.com/username/index.html. With most Web server programs, the default page that is first loaded is named index.html, so that's the name you'll use for the first page you'd like presented to users when they access your Web site.

Uploading HTML pages to the server Once you've decided on an ISP that you feel is reasonably priced, you're ready to create your HTML pages and upload them to the server. To do all this correctly, though, you'll probably need to keep these points in mind: •

Site's default URL- This should be something like the ISP's host address and a directory for your username. For instance, if your username is user1 and your ISP's Web server is www.lntinfotech.com then the default URL for Site will be http://www.lntinfotech.com/user1/. Different ISPs will organize this in different ways, so you'll need to make sure you get this right.

•

Uploading files to the site's directory- You should get instructions for accessing your Web site's directory on the Web server computer using either FTP or a UNIX shell account.

•

Limitations to the names you can give to your files- The operating system in use by the Web server may not be instantly obvious to you. If this is the case, you'll want to ask if there is a certain filename length or a certain format for naming files you need to follow.

•

Creating subdirectories within your main Web site directory- Most Web servers will give you this capability, but some will not allow you to create new subdirectories.

•

Support offered for CGI programming- Some servers wouldn’t allow you to add CGI scripts to your Web site for processing forms or adding other interactive features. At the same time, some will, but require you to pay extra or pay to have the provider write those scripts (regardless of your ability). If you plan a highly interactive site, then you should ask about CGI support.

Organizing a Web Site The most important thing to remember when organizing a Web site is how the server computer you're using will differ from the computer you use to create Web pages. This is because you'll need to know the exact path to HTML pages and multimedia files you use in creating your Web page. As we've seen before, an URL requires both a server name and a path statement to the file. This includes files that you've placed on your own Web server-so while you're creating your Web pages, you'll need to know where your files will eventually be. Training & Development Division

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Although there are a number of different ways to arrange a Web site, there are some rules of thumb to keep in mind. For the most part, any organization you create for your Web site files should be designed to make updating your pages easy in the future. If you have to move all your files around every time you change something on a Web page, you'll also be forced to change all the hypertext links on many other pages-and that can be incredibly time-consuming.

Different types of organization for Web sites: •

Single-directory sites- Smaller sites (with just a few HTML pages and graphics) can often get by with a single directory on the Web server. All your graphics and HTML pages are in this one directory. One of the biggest advantages of this system is that links to local files and graphics require no special path statements.

•

Directory by function- One way to organize more complicated sites is to put each section of related Web pages in the same directory. For instance, in your main directory you might offer only your first (index) page and its associated graphics. For a business site then, you'd have subdirectories for About the Business, Product Information, Technical Support, and so on. In each of these subdirectories, you'd include all the related HTML files and the graphics for those pages.

•

Directory by file type- Some people prefer to create subdirectories according to the type of file as opposed to the content of the page. Your main directory may have only the index page of your site. Other subdirectories might be Graphics, Web Pages, Downloadable Files, and so on. The main advantage in organizing this way is that files generally have to be replaced only once. If you use a graphic on a number of different pages, for instance, you replace it once in the Graphics subdirectory, and all the HTML pages that access this graphic will use the new one.

•

Hybrid- The best way to organize a large site might be a hybrid of the last two methods above. Creating separate subdirectories for nonrecurring items (such as individual Web pages in each category) while creating other subdirectories for items used multiple times (such as graphics) lets you get to all the files in an efficient way.

Naming Your Files We've already mentioned that file extensions are an important part of all the filenames you use for your Web site. Because other Web browsers may rely on the file extension to know what sort of document or file it is, you'll need to include the appropriate extensions with all your Web site files. Web site will almost always begin with a file called index.html. Most Web server software programs will automatically load this page if the URL of your site is accessed without a specific path and file reference. For example, entering http://www.sun.com/ in your browser actually results in the URL http://www.sun.com/index.html being loaded in your browser. Web site's first page (whether it's a "front door" page or the first page of your site) should be designed with this in mind. If you plan to offer only Netscape-enhanced pages, for instance, you'll want to let your users know this on the index.html page. The other consideration for naming your files is the organization you plan to use for your site. If you're using a single-directory organization, your filenames should be as unique as possible, and graphics and other files should probably have names that relate to associated Web pages. For instance: about_company.html about_header.jpeg about_ceo_photo.jpeg When possible, these names will help you determine which files are associated with which HTML pages when you go to update those files. For graphics and other files that show up on multiple pages, you might want to come up with a memorable prefix, like gen_ or site, just so you can easily replace these universal files when necessary.

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Example: Organizing a Site To create a reasonably sized site for home-business Web site, we are going to use the hybrid style of organization. We have three different sections on my site: About our Business, Services, and Samples. Each of these sections will have its own directory structure. Graphics will be in their own subdirectory, as will downloadable files that we are including

The directory organization for my site The directory names, then, will be as follows: about_pages service_pages sample_pages graphics sample_files Files and graphics are named for where they appear, unless they show up in multiple Web pages. For this site, the prefixes I'm using are as follows: about_ serv_samp_ gen_ index_ By naming files in this way, I'll be able to replace any graphics or update my sample files easily-without being forced to load each file or graphic to figure out what it is. Making the names as descriptive as possible (aside from the prefix) will help too, as in the following: about_photo_me.jpeg samp_resume1.doc sampl_catalog_copy.txt

Updating Your Web Site If you organize your site well, updating the site is simply a matter of replacing an outdated file with a new file using the same filename. For instance, if I wanted to replace the picture of me in the previous example, I'd simply name the new file about_photo_me.jpeg, and save it in the same directory. Now the associated Web page will load the new graphic without requiring any changes to the HTML codes. You'll need to check with your company's IS contact or your ISP to figure out exactly how you'll update files. With an ISP, you can generally use an FTP program to put new files in your directory organization on the Web site. You might instead be required to use a UNIX-based shell account for your uploading. In either case, it's a fairly simple process. Training & Development Division

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Your Web space provider will require you to enter a username and password to gain access to the Web server, whether by FTP or shell account. Generally, you will point your FTP server to the Web server itself (for instance, www.isp.com), unless the provider has created a mirror site to avoid direct access to the Web server. After clearing the security procedure, you'll most likely be in your personal Web site's main directory. (If not, you'll need to use the ‘cd’ command in UNIX or otherwise change directories in your FTP program.) From that point, you can update files using the Put command. Simply upload the updated files with the same names as the outdated files-in nearly every case, the old files will simply be overwritten. If you're using new files, upload them using the names and paths that your Web page links use to refer to them. Tip: It's a good idea to maintain a folder or directory on your own hard drive that is as identical as possible to the Web site you make available on a server-so you can test your organization and filenames.

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Review Questions 1. All HTML tags are enclosed in ____. a. < and > b. % and % c. # and # d. “ and “ 2. The simplest tool to start with HTML for Windows is a. MS FrontPage b. Notepad c. MS Word d. HTML Builder 3. The meta tag for keyword allows a. us to display its keyword on the status bar b. us to define technical words on rollover c. the site to rank higher in search engines d. the site to be indexed in external sites 4. The most recommended file name to "save as" for your homepage is a. Home.html b. Index.html c. Page.html d. Front.html

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Summary As there are certain advantages of the Web and there are certain disadvantages too. We'll need Web server software, an Internet connection, a Web URL for our pages, and a system for organizing our pages and graphics. Before we can display our HTML pages on the Web, we need access to a Web server. With most Web server programs, the default page that is first loaded is named index.html, so that's the name we'll use for the first page we'd like presented to users when they access our Web site. Smaller sites (with just a few HTML pages and graphics) can often get by with a single directory on the Web server.

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HTML, DHTML & JavaScript Chapter 3: Creating a Web Page and Entering Text

Objectives • • •

Use various tools of web designing List type of tags used in HTML pages Create a HTML page

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With the basics behind you, it's time to start creating your first HTML pages. As already been mentioned, the basic building block of an HTML page is text. To create these pages, all you really need is a text editor and a Web browser for testing your creation (you'll eventually need a graphics program to create and edit your graphics, too). So let's look at the basic tools for Web publishing, and then create your own HTML template.

The Tools for Web Publishing We have already mentioned it above all you need is a text editor. In Windows 95, that's Notepad or WordPad. For Mac users, SimpleText is the perfect HTML editor. UNIX users can opt for VI or Emacs. Basically, all you need to remember is that HTML pages, while they include the .htm or .html file extensions, are simply ASCII text files. Any program that generates ASCII text files will work fine as an HTML editor-even a word processor like WordPerfect or Microsoft Word. Tip: If you create an HTML page in a word processor, don't forget to use the Save As command to save it as an ASCII text file. We'll also need a Web browser to check on the appearance of your Web page as you create it. All Web browsers should have the ability to load local pages from your hard drive, just as they can load HTML pages across the Web. Check the menu of your Web browser (if it's a graphical browser) for a command like File,

In Microsoft Internet Explorer for Windows XP, the File, Open command opens the Open Internet Address dialog box which contains an Open File command button to open a file from a drive

You may have heard of some dedicated HTML editing programs that are designed to make your work in HTML easier. They do indeed exist, and they can be very useful. Unfortunately, many of them also hide the HTML codes from the designer, so they would be difficult for us to use as you learn how HTML works. Once you understand HTML, though, it can be a great benefit to use one of these browsers.

Document Tags The first HTML tags we're going to look at are the document tags. These are the tags that are required for every HTML page we create. They define the different parts of the document. Just like a magazine article, an HTML document has two distinct parts-a head and a body. The head of the HTML document is where you enter the title of the page. To create the head portion of HTML document and to give the document a title, type the following in your text editor: My First Page This tells a Web browser what information should be considered to be in the head portion of the document, and what it should call the document in the title bar of the browser window. Training & Development Division

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The body is where we'll do most of our work-you'll enter text, headlines, graphics, and all our Web goodies. To add the body section, start after the tag, and enter the following: Between these two tags, you'll eventually enter the rest of the text and graphics for your Web page. There's one last thing you need to consider, in order that all Web browsers understand that this is an HTML document (remember that you're saving it as ASCII text, so the browser could be confused), you need to add some tags on either side of the head and body tags you've created. Above the first tag, enter the following: After the last tag, type the following: Now, at least as far as your Web browser is concerned, you have a complete Web document! Example: Creating an HTML Template Let's take what you know and create a template. By saving this template as a generic text file, you'll have a quick way to create new HTML files-simply load the template and use the File, Save As command to save it as your new Web page. Start by entering the following in a blank text file: Enter Title Here Now save this as an ASCII text file called template.html (or template.htm if you're using DOS or Windows 3.1). Now, whenever we are ready to create a new HTML document, simply load template.html into your text editor and use the Save As command to rename it. Example: Hello World When learning a new programming language, it's traditional that the first program you create is designed to say "Hello World." Well, HTML isn't a programming language-but I can use the Hello World example to prove that your template is a complete Web document. Load the template.html file into your text editor, and use the Save As command to rename it hello_world.html or something similar. Now, edit the document so that it looks like this: Hello World Page Hello World! Select the File, save command from your text editor. Now load our Web browser and select the Open File (or similar) command from the File menu. In the dialog box, find the document hello_world.html and select OK to load it into your Web browser. If everything goes as planned, your browser should display something similar to the diagram below.

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The Hello World page as viewed in Microsoft Internet Explorer.

Understanding Tags: Container and Empty Tags In creating your HTML template, you've already dealt with some of the most basic tags in HTML. The first thing you should notice about these HTML tags is that all tags include < and > on either side of the tag's command. This is how HTML recognizes tags. If you don't use the brackets, then a Web browser will assume your commands are text that you want displayed-even if that text is the same as an HTML command. While a Web browser would consider the following to be a tag: that same Web browser would interpret the following as text to be displayed on-screen: HTML Tip: Tags are not case-sensitive, so they don't have to be all uppercase-even though that's how they appear in this book. I suggest you type them as uppercase, though, since it makes them stand out in your text editor. Because tags aren't considered text by the document, they also don't show up in the document. If the browser interprets something as a tag, it won't appear in the browser window. Container Tags You may have noticed that for every tag, such as the title tag, you actually entered two different HTML commands-an "on" tag and an "off" tag. The off tag is the same as the on tag, except for the / after the should be ignored by the browser. Even multiple lines are ignored-as with most tags, the comment tag ignores returns. Generally, you'll use the comment tag for your own benefit-perhaps to mark a point in a particular HTML document where you need to remember to update some text, or perhaps to explain a particularly confusing part of your page. Since it's fairly easy for anyone to view your raw HTML document, you might also use the comment tag to create a copyright message or give information about yourself. Viewing the Source of Web Pages: Ever been out on the Web looking at a particularly well-designed HTML document-and wondering how they did it? If you'd like to, most browsers will let you view the document source for any Web page they can load. This allows you to download the raw HTML codes and ASCII text, just as if you'd created the page yourself. To do this, select the View Document command in the Edit menu of your Web browser (the command may differ slightly, so look for a similar name if you can't find View Document). What results is the plain ASCII text file that was used to create that Web page. Depending on your browser, this source file will either be displayed in the browser window, or saved to your hard drive and displayed in the default text editor. If the source is displayed in the browser window, then select File, Save As to save the source to your hard drive. Now you might be able to imagine how comments can come in handy. If you would rather not have people copy and use the source from your Web pages (or if your pages contain otherwise copyrighted material that you want to protect), you can use the comment tag to let others know that you consider the page your property. For instance: Of course, that's not to say that you shouldn't also offer a visible copyright notice or other legal disclaimers. But comments within the code tend to talk directly to folks a little more HTML-savvy. Using a comment tag like this is a great way to encourage other Web designers to ask you before using your HTML pages for their own private use.

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Review Questions 1. What does HTML do? a. It processes code to form a program b. It interprets code and display it on screen c. It contains instructions for the browser to work d. It is the language used to create websites 2. How to insert comments in HTML? a. b. c. d. 3. The Browser applies the feature of a tag until it encounters _____ tag. a. Quit b. Closing c. Exit d. Deactive 4. _______are the HTML codes that control the appearance of the document contents a. Tags b. Codes c. Slashes d. Properties 5. State True or False. HTML Tags are case sensitive. a. True b. False

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Summary Basically, all we need to remember is that HTML pages, while they include the .htm or .html file extensions, are simply ASCII text files. We'll also need a Web browser to check on the appearance of our Web page as we create it. All Web browsers should have the ability to load local pages from our hard drive, just as they can load HTML pages across the Web. Document tags are the tags that are required for every HTML page we create. In HTML, tags that include both an ‘on’ and an ‘off’ tag are called container tags. Some tags in HTML fall into one other category, called empty tags. These tags have only ‘on’ tag-there are no ‘off’ tags.

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HTML, DHTML & JavaScript Chapter 4: Changing and Customizing HTML Text

Objectives • • •

To use header and headline in document Quoting, Definitions, and Addresses

To Preformat the text

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Creating Headers and Headlines Header tags are containers, and unlike many other HTML tags, they double as paragraph tags. Ranging from level 1 to level 6, headers allow you to create different levels of emphasized headlines to help you organize your documents. The following is an example; see following figure for the results:

HTML header tags at work. Notice that the fourth entry is regular text between and tags. Header Level One is the largest for headlines or page titles Level Two is a little smaller for major subheads Level Three is again smaller, for minor subheads This is regular text. Level Four is about the same size as regular text, but emphasized Level Five: again emphasized, but smaller than regular text Level Six is generally the smallest header We cannot include a header tag on the same line as regular text, even if we close the header tag and continue with unaltered text. A header tag has the same effect as a , in that it creates a new line after it’s "off" tag. The following: This is a header And this is plain text. offers the same results as: This is also a header And this is also plain text In both cases, the Web browser will place the header text and plain text on different lines, with the header text appearing larger and the plain text appearing "normal" in size. Note: The HTML standard technically requires that using a particular header level requires that the larger header tags be used previously. So, for instance, if you use an tag, you should have an tag somewhere before it. Very few browsers (if any) actually require this and, for the most part, HTML designers use header tags as simply a way to change the size of text for emphasis. That's how I use them, even going so far as to use or for "fine print" on my pages. If you're an absolute stickler for standards, though, realize that it's more correct to only use header tags for true headers in your documents, and then only in order (i.e., , , , and so on).

Implicit and Explicit Text Emphasis Implicit tags are those that allow the browser to choose, within limitations, how the marked-up text will be displayed. Header tags are actually an example of an implicit tag, since the HTML designer has no control over how much bigger or smaller a header tag will be. Although most browsers will render Training & Development Division

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header tags in somewhat similar ways, others (for instance, nongraphical browsers) have to come up with another system for emphasis, such as underlining or highlighting the text. Because HTML was originally created with the overriding mission of being displayed on nearly any computer system, implicit tags for emphasis were a necessity. HTML allows the designer to decide what text will be emphasized. But only explicit tags tell the Web browser how to render that text. Explicit Styles Explicit tags are also often called physical tags, since they very specifically tell the Web browser how you want the text to physically appear. The browser is given no choice in the matter. The basic explicit tags are containers that let the user mark text as bold, italic, or underlined. Tags

Meaning

,

Bold text

,

Italic text

,

Underlined text HTML Physical Container Tags

Note: Not all browsers will render underlined text (notable among them is Netscape Navigator), because hypertext links are also often displayed as underlined, which could potentially be confusing. With these tags, the browser really has no choice-it must either display the text as defined or, if it can't do that, then it must add no emphasis to the text. If we prefer that text not be emphasized at all if it can't be italic, for example, then we should use the tag. Another feature of explicit (physical) tags is that they can generally be used in combination with other tags. As we'll see in the next section, this isn't always a good idea with implicit tags. For instance, most graphic browsers will render the following example by applying both tags to the text

Most browsers can render two physical tags applied to the same selection of text. Welcome Home! This is bold and italic

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Implicit HTML Tags Implicit styles are often called logical styles, since they allow the browser some freedom in how it will display the text. These tags, like the header tags, are generally relative to one another, depending on the browser being used to view them. Some of the common implicit (logical) tags Tags

Meaning

Generally Rendered as…

,

Emphasis

Italic text

,

Strong emphasis

Bold text

Teletype

Monospaced text

,

Some Basic Logical HTML Tags Above table includes a section that tells you how these tags are often rendered in graphical Web browsers. There's no rule for this, though, and the tags don't necessarily have to be rendered in that way. There are two other distinctions between these tags and the physical tags (such as bold and italic) that you've already discussed. First, any Web browser that views them will always render these logical tags. Even text browsers (which are unable to show italic text) will display the or tags by underlining, boldfacing, or highlighting the text. Second, these tags are generally not effective when used together. Where text will sometimes offer useful results, text rarely will. Combining these tags with other tags (such as header tags or physical tags) is often either ineffective or redundant.

Other Implicits: Programming, Quoting, and Citing At the beginning of this chapter, I mentioned that the creation of HTML tags took place before the standard was ever conceived of-which might explain some of the tags that we discuss in this section. For the most part, these tags are implicit (logical) and aimed directly at certain areas of expertise. At the same time, however, the bulk of these tags will look exactly the same in a Web browser. Programmer's HTML Tags One of the early, more common uses for HTML was for documenting computer programs and offering tips or advice to computer programmers. Part of the HTML 3.0 standard, then, offers some implicit (logical) HTML tags that allow HTML designers to mark text in a way that makes it easier to present computer-programming codes. Those tags are listed in table below. Tags

Meaning

Generally Rendered as…

,

Programming lines

Monospaced (like )

,

Keyboard text

Monospaced

,

Sample output

Monospaced

Variable

Italic

,

HTML Tags for Computer Programming Notice that the majority of these tags are often displayed in exactly the same way-in the default monospaced font for the browser. Then why use them? First, not all browsers will necessarily follow the "general" way. Some browsers will actually render these tags in slightly different ways from one another, so that , for instance, might appear in a slightly larger font than . Second, using these tags is a great way to internally document your HTML pages, so that you can tell at a glance what certain text is supposed to be. This will help you later when you return to the document to update it or fix errors-especially as the document becomes more complex.

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Quoting, Citing, Definitions, and Addresses Along the same lines as the HTML "programmer's" tags, you have available certain implicit tags that work as typographer's or publisher's codes. As shown in below table, these codes often work in ways similar to others you've already seen-with a few twists. Tags

Meaning

Generally Rendered as…

,

Bibliographical citation

Italic text

,

Block of quoted text

Indented text

,

Term definition

Regular text

Street or e-mail address

Italic text

,

HTML Publisher-Style Tags Again, notice that the tag isn't going to be rendered any differently from the italics, emphasis, or variable tags we've seen previously. The tag is often not rendered as any special sort of text at all, whereas the tag is identical in function to the italics tag. So the best use for these tags (with the exception of the tag) is as internal documentation of your HTML documents. Example: Using the and Tags The only really new tag in the above table is the tag. This tag usually indents the left margin of regular text in the browser window, just as you might find a blocked quotation formatted in a printed document. Also as part of the tag, generally adds a return or one extra line on either side of the tag, so no paragraph tags are needed. Paragraph tags should, however, be used to contain text on either side of the blockquote. Although the tag is similar to italics or emphasis, I've thrown in an example of using it correctly. Remember to include a line break after each line of the address. Listing -between the body tags. The and Tags I believe it was Abraham Lincoln who once said (emphasis is mine): Four score and seven years ago our forefathers brought forth on this continent a new nation, conceived in liberty and dedicated to the proposition that all men are created equal. It was something like that, wasn't it? If you liked this quote, feel free to write me at: Rich Memory 4242 Sumtin Street Big City, ST 12435 Notice that an off paragraph tag isn't required before you get into the address tag-remember, works very much as italics does, and the tag is designed to work as well inside a paragraph container as it does outside one. So you can put the paragraph tag after the address, to contain both address listing and the text in the same paragraph. Take a look at next figure , unlike some of the tags you've looked at, really does offer unique abilities that make it worth using in your documents.

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Blockquote and address HTML tags.

Preformatted Text The HTML 3.0 standard is not designed for layout. In fact, you haven't even learned how to put two blank lines between paragraphs. We've also said that spaces and returns in between tags (like the paragraph tag) don't matter. Well, there is at least one exception to this rule: the tag. The (preformatted text) tag is designed to allow us to keep the exact spacing and returns that we've put between the on and off tags. The basic reasoning behind this tag is the notion that every once in a while we'd like your text to stay exactly as we put it-for instance, in a mathematical formula, or if we create a table. While there are other ways to do both tables and math, they don't fall under the HTML 3.0 standard. On top of that, you can use for a number of other reasons: lists, lining up decimals for dollar figures, and even poetry. Consider the following example: Oh beautiful, for spacious skies, For amber waves of grain. For purple mountains' majesty, Above the fruited plains. Sure it's a familiar refrain, but it won't look so familiar in a browser if we leave it between paragraph tags. Instead, we can use the tag to keep things exactly the way we want them: Oh beautiful, for spacious skies, For amber waves of grain. For purple mountains' majesty, Above the fruited plains. In a browser, it'll look exactly the way we want it to

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Paragraph versus preformatted text

We have noticed that the preformatted text is in a monospace font, it will always be that way. Otherwise, the tag works pretty much like the paragraph font, except that it lets us decide where the line breaks and spaces will appear. Look at the following example: I simply want to make this really clear to you. With the above code, the browser will display this line in nearly exactly the same way as it would using the tag, except that it will be in a monospace font, and the extra spaces and extra return will appear as well. In fact, there will be two blank lines below the line of text-one for the return, and one for the tag itself. We can even use the tags to create extra lines in a document without typing any text between them. This example adds two blank lines to a document: For each additional blank line you want to add, just press Enter after the first tag one time. Note: There is one potential drawback to the tag. It doesn't allow the browser screen to wrap text automatically-instead; users need to expand their browser window if we use particular long lines within a container. Just keep this in mind, and make sure your lines of text are reasonably short so that all browsers can view them without scrolling.

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Example: Using for Spaces and Tables In the same way that we created the film script using the tag, we can also format a primitive table using the tag along with some others. The key to making this work correctly is alignment. Realize that each space taken up by a character of an invisible tag (like ) will not appear in the browser's display, so we'll need to compensate. Tip: One way to keep the columns in a table straight is to type your table first, and then add emphasis tags afterward. Load your template and save it as pre_tbl.html. Now enter listing between the body tags. Price Per Item in Bulk Orders Quantity 1-50 50-99 100-200 200+

XJS100 $40 $35 $30 $25

RJS200 $50 $45 $40 $35

YJS50 $75 $70 $65 $55

MST3000

$100 $95 $90 $75

Prices do not include applicable sales taxes. You may need to play with the spacing a bit to line everything up. Save the HTML document, and then choose the Open File command in browser to proof it. Keep playing with it until it looks right. Once we have everything aligned correctly, it's actually a fairly attractive and orderly little table

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Review Questions 1. The page title is inside the ____ tag. a. Body b. Head c. Division d. Table 2. All normal webpages consist of what two parts? a. Top and bottom b. Body and Frameset c. Head and Body 3. Which of the following will NOT be found in the section? a. Metatags b. Table c. Title d. None from the Above 4. Which section is used for text and tags that are shown directly on your web page? a. Head b. Body c. Foorter d. All of the above options 5. To specify a font for your whole page add which tag? a. b. c.

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Summary Header tags are containers, and unlike many other HTML tags, they double as paragraph tags. Browsers can render two physical tags applied to the same selection of text. Part of the HTML 3.0 standard, offers some implicit (logical) HTML tags that allow HTML designers to mark text in a way that makes it easier to present computer-programming codes. Various publisher tags can be used to make designing of web pages attractive. Preformatted text tag is designed to allow us to keep the exact spacing and returns that we've put between the on and off tags.

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HTML, DHTML & JavaScript Chapter 5: Displaying Text in Lists

Objectives • • •

To list content of page by using List tag Use Directories, Definitions, and Menus Quoting Definitions, and Addresses

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Using Lists in HTML List tags, like paragraphs and preformatted text, are generally HTML containers that are capable of accepting other container and empty tags within their boundaries. These list tags are responsible for affecting the spacing and layout of text, not the emphasis, so they are applied to groups of text, and allow individual formatting tags within them. Most HTML lists are created following the form: First item in list Second item in list Third item Each of the items appears on its own line, and the tag itself is generally responsible for inserting either a bullet point or the appropriate number, depending on the type of list that's been defined. It's also possible that the tag could insert no special characters (bullets or otherwise), as is the case with definition listings. You'll look at each type in the following sections. The basics to remember are to use the main container tags for list type and the individual empty tags to announce each new list item. The type of list you choose is basically a question of aesthetics. Ordered and Unordered Lists It might be better to think of these as numbered (ordered) and bulleted (unordered) lists, especially when we're talking about their use in HTML. The only drawback to that is the fact that the HTML codes for each suggest the ordered/unordered names. For numbered/ordered lists, the tag is , and for bulleted/unordered lists, the tag is . For either of these lists, a line item is designated with the empty tag . In the case of ordered lists, the tag inserts a number; for unordered lists, it inserts a bullet point. Examples of both follow. The following is an ordered list: Item number one. Item number two. Item number three. And here's an unordered list: First item. Second item. Third Item.

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The subtle differences between ordered and unordered lists As we’ve already mentioned, both ordered and unordered lists can take different types of internal HTML tags. It's even possible to include paragraph, line break, and header tags in lists. While you may see the potential in creating ordered lists that conform to standard outlining conventions (for instance, Roman numerals and letters), HTML 3.0 doesn't really help much. There is no way to change the number from Arabic numbers, and there's no way in HTML 3.0 to create a list that starts with something other than 1. Netscape, however, has added both of these abilities, and you can be much freer in your outline, as long as you warn your users ahead of time to view your page with Netscape Navigator (or a Netscape-compatible browser).

Directories, Definitions, and Menus Your other lists have something in common with one another that they don't share with ordered and unordered lists: all of them use some permutation of the previous line-item system, but none of them consistently use numbers or bullets. Directories and menus are basically just plain lists. Definitions are unique among all lists because they offer two levels of line items within the list structure-one for the definition item and one for the definition itself. Directory and Menu Lists To create a directory or menu list, you start with its respective container tag: or . Of these two, the directory list is probably more useful. Most browsers don't currently render the command consistently some use a bulleted list, others use no bullets. The following is an example of : House Salad Fresh Soup of the Week Buffalo Wings Escargot Liver and Onions Turkey Sandwich, open faced Turkey Sandwich, pre-fab

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Note: You might use the tag when creating a list of hypertext links. It's thought that future interpretations of the menu list may be built into future browsers, and that designers will eventually see more benefit in using the tag. In theory, the tag is a little more limiting. It's designed as a mechanism for listing computer file directories in HTML pages. Technically, it doesn't support interior HTML tags, although most browsers will display them. The tag is also supposed to be limited to 24 characters (for some unknown reason) and show the filenames in rows and columns, like a DIR/W command in MS-DOS, but the bulk of browsers seems to ignore both of these constraints as well, as in the following example: autoexec.bat config.sys .signature .password System Folder commaand.com .kernel Most browsers (including Netscape) will use the same font and layout for menus and directories, as they will for unordered lists. In some cases, browsers will display one or the other (more often directory lists) without a bullet point, which can make them mildly useful. Some browsers can be set to a different font for directories and menus (versus ordered lists). So you may want to use these types, if only because some Web-savvy users' browsers will make an effort to display them differently (as shown in below figure).

Menu and directory lists in MS Internet Explorer

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Definition Lists The final list tag is the definition list, which is designed to allow for two levels of list items, originally conceived to be the defined term and its definition. This is useful in many different ways, though, and is also nice for its consistent lack of bullet points or numbering items (as opposed to the menu and directory listings, which are often rendered haphazardly by browsers). The tags for this list are the container tag (definition list) and two empty tags, (definition term) and (definition). The tag is designed (ideally) to fit on a single line of your Web page, although it will wrap to the beginning of the next line if necessary. The tag will accept a full paragraph of text, continuously indented beneath the term. The following is an example of all three tags: hero (n.) A person admired for his or her brave or noble deeds. hertz (n.) A unit used in the measurement of the frequency of electromagnetic waves hex (n.) An evil spell or magical curse, generally cast by a witch. Notice that standard HTML mark-up is permissible within the boundaries of a definition list, and that using bold and italics for the defined terms adds a certain dictionary-like quality.

A basic definition list

Tip: Not all browsers will display definition lists in the same way, so adding spaces to items (to get them to line up with the text) is often a waste of time. It should also be pointed out that just because definition lists allow for two different types of list items, you needn't necessarily use both. Using just the tag in your list, for instance, will result in a list not unlike an unordered list-except that nearly all browsers will display it without bullets: Milk Honey Eggs Cereal And, although more difficult to find a use for, the item could be used on its own to indent paragraphs repeatedly. I must say that I was shocked at his behaviour. He was: Training & Development Division

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Rude. Not rude in your standard sort of affable way, or even in a way that would be justifiable were he immensely wealthy or critically wounded. It was just a rudeness spilling over with contempt. Unjust. If there was something he could accuse you of falsely, he would do it. I could almost see him skulking around his apartment after a particularly unsuccessful party, doing his best to find things stolen, which he could blame on people who hadn't actually bothered to show up. The definition list offers some additional flexibility over the standard lists, giving you more choices in the way you layout the list items.

Definition lists using only one of the two elements

Nesting Tags and Combining List Types Since most of your HTML lists can accept HTML tags within their list items, it stands to reason that you could potentially create lists within lists. In fact, creating a list, then creating another list as part of an item in that first list is how you can create an outline in HTML. Nesting Tags The idea of nesting comes to us from computer programming. Nesting is essentially completing an entire task within the confines of another task. For HTML, that means completing an HTML tag within the confines of another container tag. This could be something like the following: She was easily the most beautiful girl in the room. This is an example of correctly nesting the tag within a paragraph container. On the other hand, many browsers would still manage to display this next code: She was easily the most beautiful girl in the room. But this second example is really poorly constructed HTML. It often works, but the tag isn't properly nested inside the . In this example, that doesn't matter too much, since you can still reason out what this statement is trying to do. With lists, however, things can get complicated. So it's best to remember the "nesting" concept when you begin to add lists within lists. As far as HTML is concerned, a nested list works as marked-up text within the previous list item. When the next list item is called for, HTML moves on. Training & Development Division

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Lists within Lists Let's look at an example of a simple nested list: Introduction Chapter One Section 1.1 Section 1.2 Section 1.3 Chapter Two Tip: It's a good idea to indent nested lists as shown in the example. The browser doesn't care-it just easier for you (or other designers) to read in a text editor. (Regardless of your spacing, most browsers will indent the nested lists-after all, that's the point.) Notice that the nested list acts as a sublevel of the Chapter One list item. In this way, we can simulate an outline in HTML. Actually, the nested list is just HTML code that is part of the Chapter One list item. As we saw in below listing you can use the tag to create a line break in a list element without moving on to the next list item. Following the same theory, an entire nested list works as if it's a single list item in the original list. The following: Section Five This section discusses ducks, geese, finches and swans. Section Six is essentially the same as the list that follows: Section Five Ducks Geese Finches Swans Section Six In both cases, the nest HTML container is simply a continuation of the first list item. Both the text after the in the first example and the ordered list in the second example are part of the list item labelled Section Five.

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In both of the examples, the HTML container is simply part of the list.

Combining List Types When nesting lists, it's also possible to nest different types of lists within one another. This is useful when you'd like to vary the types of bullets or numbers used in an outline form. For instance: Introduction Company Financial Update First Quarter Second Quarter Third Quarter Fourth Quarter Advertising Update Results of Newspaper Campaign Additions to Staff New Thoughts on Television Human Resources Update

There's nothing terribly difficult to learn here-just the added benefit of being able to nest different types of lists within others. You're still simply adding HTML markup code to items in the original list. This time, however, you have more choice over how your outline looks (see fig. 6.6).

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Nesting different types of lists

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Review Questions 1. To separate single list items use? a. and b. and c. and d. and < /list> 2. When making bulleted lists you have what options? a. square, disc, polygon b. disc, circle, square c. triangle, square, circle d. No other shapes than default 3. To start a list using circles use which of these tags? a. b. c. d. None from the Above 4. To create a list using lowercase letters use? a. b. c. d. Any one of the above options 5. tags will create what kind of list? a. Numbered List b. Bulleted List c. Grocery List

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Summary To list content of page, List tags can be used. tag can be used while creating a list of hypertext links. Like MENU, Definition Lists can be used for two levels of list items. Nesting of Tags is possible if we want to show nested lists. We can combine more than one type of lists together to give better look to our web pages. Depends on users choice we can change default shapes of bullets or we can change numbering style as well.

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HTML, DHTML & JavaScript Chapter 6: Adding Graphics to Your Web Pages

Objectives • • •

Use Images in web page Types of graphics that can be added to web page Creating and Manipulating Graphics

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Now that we've seen many ways we can add some character to our text-and use different tags to better communicate your ideas-it's time to jazz up your pages a little bit. Let's add some graphics! First, though, we should know a couple of important things about placing graphics. Some of these considerations may seem a bit foreign to you, especially if we're a graphic designer or commercial artist. We have to think in a slightly different way about graphics for your HTML pages.

The Special Nature of Graphics on the Web One may be comfortable using a program such as CorelDraw! Or Adobe Photoshop to create and manipulate graphics, But if we've never done any design for the World Wide Web, there's also a good chance that we've never worried about one special graphics issue, even if we are a print design expert. How big is the graphics file that we created? Aside from using the correct graphics format, this issue is the single most important consideration in graphical Web design. The Size of Graphics Files Why is the size of graphics files so important? Our Web users have to download our pages to view them, including all the graphics associated with the pages. Couple that fact with the Web speed issues discussed in previous Chapter and the need for smaller graphics files becomes apparent. The high-colour, high-resolution graphics files that colour printers and professional designers work with are generally measured in the number of megabytes of information required to create the graphics file. Each image can take up more space than is available on a floppy disk. Often, special tapes and cartridges are required to transfer these files from the graphics shop to the printer. A good average size for a Web graphic, on the other hand, is between 10K and 30K-about one to three percent of the size of those high-colour, high-resolution graphics. This could be tough. Picking Your Web Graphics File Type The other thing that you need to concern yourself with is the file type that we're going to use for Web graphics. In general (at least currently), we can choose either of two file types: GIF and JPEG. GIF (CompuServe Graphics Interchange Format) is the more popular among Web browsers, but JPEG (Joint Photographic Experts Group) is gaining popularity and becoming more widely used. GIF and JPEG bring different advantages to the table. GIF Format Graphics Any graphical browser supports the display of GIF format files inline, meaning that the browser doesn't require a special viewer for these files. GIFs are compressed graphics, but they tend to lose less image clarity than JPEGs. Images that have smaller colour palettes (those that use 256 colours or fewer) often look better in GIF format. GIF is also the file format of choice for creating transparent graphicsgraphics that make the Web page appear to be the actual background of the GIF graphic. Although GIF files are compressed, they tend to be a bit larger than JPEGs, but they decompress more quickly and tend to be drawn more quickly than JPEGs (given the same file size). Another problem with the GIF file format is the fact that it includes certain copyrighted elements that make it less than an open standard for graphics interchange. The JPEG Format Gaining on GIF in popularity is the JPEG format, which is widely used by Web designers. JPEG graphics can be viewed in most new graphical browsers without a special helper application. JPEG graphics have the advantage of being better for graphics that have more colors (up to 16.7 million, in most cases) than similar GIF files; in addition, the JPEG files are smaller (look ahead to fig. below). Also, the compression scheme is in the public domain.

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The paint Shop Pro interface On the down side, JPEGs can be a little glossier than GIFs, meaning that the higher rate of compression results in slightly lower image quality. JPEGs also take a little longer to decompress than do GIF files. So although the smaller size of JPEG files allows them to be transmitted over the Internet more quickly, the amount of time that it takes to decompress those files sometimes negates this advantage.

Creating and Manipulating Graphics It's no secret that a lot of Web design has transitioned from manipulating text-based HTML documents to designing and integrating compelling graphics into Web pages. As the Web has become more commercial, its graphical content has become more professional. If we're not up to the task of creating professional graphics, don't worry too much; programs are available that will help you. Also, it's more important that graphics further the usefulness of the text. The graphics in and of them are not the point. The point is to make our Web pages more exciting and informative. It is a fact, however, that Web sites are leaping forward daily into a more professional, more graphical presentation of Web-based information. Commercial artists and designers are continuing to find new niches on the Web. If we're a skilled computer artist, congratulations; this is where we'll put your skills to use. If we're not, that's OK, too. Any Web designer needs to be able to manipulate and edit graphics in a program such as Adobe Photoshop or CorelDraw! But we don't necessarily have to create those graphics, if that's not your forte. Creating Graphics for the Web As we get started with a program such as Photoshop or CorelDraw! Keep in mind that the most important consideration in creating Web graphics is the file size. File size isn't generally the first consideration for creating print graphics; almost any print shop or prepress house will accept large storage cartridges or tapes that provide access to your huge full-colour graphics. Not on the Web. Our target is as small as possible-between 15K and 35K for larger (bigger on the screen) files. We can come up with graphics to use on your Web pages in many ways. Eventually, any graphic that you use needs to be in a standard file format (for example, GIF or JPEG) and relatively small. But how you come up with the final graphic has a lot to do with the information that you're trying to communicate and with your skills as an artist. The following are some of the different ways you might come up with Web graphics: Training & Development Division

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Create graphics in a graphics application: Many programs for both professional and amateur artists can output GIF- or JPEG-format files for use on the Web among these programs like Adobe Photoshop, CorelDraw! Fractal Painter and Fractal Dabbler. Tip: Any graphics program, even Microsoft Paint, can create Web graphics, although you may need to use another program to change the graphic to an acceptable file format. Download public-domain graphics: Tons of sites on the Internet allow us to download icons, interface elements, and other graphics for our Web site. At the same time, public-domain clipart collections (such as those available on CD-ROM) can be useful for Web pages. Use scanned photographs: Using scanned photographs (especially those that we've taken yourself) is a great way to come up with graphics for your Web pages. Unless you have access to scanning hardware, though, you may need to pay someone to scan the photos. Digital cameras: Cameras are available that allow us to take photos that can be downloaded directly from the camera to your computer. While some of this equipment can be very expensive, cameras under $500 do exist, and those photos can easily be converted for use on the Web. Use Photo CDs: Many photo development shops can create digital files of your photographs (from standard 35mm film or negatives) and save those files in PhotoCD format. Most CD-ROM drives allow you to access these photos, which you can then change to GIF or JPEG format and display on your Web pages.

Embedding Graphics in Web Pages To add graphics, we use an empty tag called the (image) tag, which we insert into the body section of your HTML document as follows: Or SRC accepts the name of the file that we want to display, and image URL (or path/filename) is the absolute (full URL) or relative path (for a local file or a file in the current directory) to the image. As the first example shows, we can display on our page any graphic file that is generally available on the Internet, even if the file resides on a remote server. For graphics files, however, it is much more likely that the file is located on the local server, so a path and filename are sufficient. We could enter the following text in a browser: This is a test of the Image tag. Here is the image I want to display: In this case, is a relative path URL, suggesting that the file image1.gif is located in the same directory as the HTML document. A browser as shown in figure below would display the result:

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Displaying inline graphics on a Web page

An absolute URL is essential, however, if we were accessing an image on a remote site, as in the following example: (This example is fictitious.) Please realize that using a URL to a distant site on the Internet causes that site to be accessed every time this tag is encountered on your page, so you should probably have some sort of arrangement with that Web site's system administrator before you link to a graphic on their server. Adding Graphics to Other HTML Tags We can add graphics links to HTML tags to do various things, including placing graphics next to text (within paragraphs) and even including graphics in lists. The following example displays the graphic flush with the left margin, with the bottom of the text that follows the image aligned with its bottom edge: It's time to start our adventure in the world of the Web. As you'll see below, there is much to learn. Words at the end of the first line wrap below the image

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Another popular use for graphics is including them in HTML lists. Best suited for this task is the (definition) list, which allows you to use your own graphics as bullet points. (Ordered and unordered lists display their numbers or bullets in addition to the graphic.) A (definition term) tag can accept more than one (definition) element, so you can create a bulleted list as follows: Our new products These absolute URLs can get rather tedious, not to mention the fact that if you happen to change the name of your Web server or move your site to another basic URL, we'll probably have to edit every page in your site to reflect the new URLs. Adding the Tag The tag is used to establish the absolute base for relative URLs used in your document's hypertext links. This tag is especially useful when your Web pages may appear in different subdirectories of a single main directory, as in some of the organizational types discussed before. The format of the tag is as follows: Training & Development Division

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Note that the tag is designed to appear only between the tags. It may be helpful to think of as doing something similar in function to a DOS path statement. The tag tells the browser that relative URLs within this particular Web document are based on the URL defined in the tag. The browser then assumes that relative URLs derive from the URL given in the tag and not necessarily from the current directory of the HTML document. Consider a document named http://www.Dreamcorp.com/products/list.html that looks something like this: Page One Back to Index In this example, the browser tries to find a document named index.html in the directory products, because the browser assumes that all relative addresses are derived from the current directory. Using the tag, however, changes this example a bit, as follows: Page One Back to Index Now the browser looks for the file index.html in the main directory of this server, regardless of where the current document is stored (such as in the products directory). The browser interprets the relative URL in the anchor tag as though the complete URL were http://www.Dreamcorp.com/index.html. Tip: If you plan to create a large Web site, you may want to add the tag (complete with the base URL) to your HTML template file. Using the tag to point to your Web site's main directory allows you to create the different types of organization systems described in Chapter 5 by using relative URL statements to access HTML documents in different subdirectories.

Creating Links to Other Internet Services Here's where the real power of URLs comes into play. Remember that an URL can be used to describe almost any document or function that's available on the Internet? If something can be described in an URL, a hyperlink can be created for it. In the following section, we start with e-mail. Hyperlinks for E-Mail Messages Creating a hyper linked e-mail address is simple. Using the mailto: type of URL, we can create the following link: Send me e-mail In many graphical browsers, this URL often loads an e-mail window, which allows you to enter the subject and body of an e-mail message and then send it via your Internet account. Even many of the major online services support this hyperlink with their built-in e-mail systems.

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Clicking a mailto: link brings up an e-mail message window Not all Web browsers accept the mailto: style of URL, however, and most of those don't return an error message. If we use this type of link, you may want to warn users. Something like the following text should work well for users of no graphical browsers: If your browser supports the mailto: command, click here to send me an e-mail message. Other Internet Services Links can be created for all types of Internet services. E.g. Gopher sites, for example, a hypertext link might look like the following example: the Library of Congress Gopher Most Web browsers can display Gopher menus. In most cases, clicking a gopher link points the browser at the Gopher site, and the Gopher menu appears in the browser window. You can create links that cause the Web browser to download a file from an FTP server, as follows: You can also downloadthe latest version of our software. When the connection to the FTP server has been negotiated, the file begins to download to the user's computer. Depending on the Web browser, this file may not be formatted correctly. Each browser needs to be set up to accept files of a certain type (such as the PKZip format file in the preceding example).

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Note: Most browsers can accept hyperlinks only to anonymous FTP servers. We generally should not include in our HTML documents links to FTP servers that require usernames and passwords. Again, most browsers have some mechanism (sometimes built into the browser window) for reading UseNet newsgroups. Some browsers launch a separate program to read UseNet groups. In either case, you can create a link like the following: UseNet Help Newsgroup This link loads whatever UseNet reading features the browser employs and displays the specified newsgroup (see fig. below). The news: URL type does not require a particular Internet server address to function. Each browser should be set up with its own links to the user's news server.

Explorer after clicking a link to the newsgroup news

Other Links for the Tag We can create a couple more tags in the section of your HTML documents. The two tags discussed in the following sections are and . The Tag The tag is designed to establish a hypertext relationship between the current document and another URL. Most of the time, the tag does not create a click able hypertext link in the user's Web viewer window. It's a little beyond the scope of this book, but programs can be written to take advantage of the tag, such as a program that creates a toolbar that makes use of the relationship defined. The tag generally has either of the following formats: Or For the most part, is used to create an author-defined structure to other HTML documents on a Web site. The attribute REL, for example, defines the relationship of the HREF URL to the current document. Conversely, REV defines the relationship between the current document and the HREF'ed URL. Training & Development Division

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Following are two examples of statements: In the HTML 3.0 standard, these definitions are relatively irrelevant-at least publicly on the Web. We more commonly find these statements used within certain organizations (perhaps companies employing an intranet), especially for advanced Web-based documentation efforts and for efforts that use HTML and SGML together. HTML 4.0 more than likely will introduce more widespread use of the statement and other tags for more tangible benefits. We may want to use one frequently: the REV="MADE" link, which tells users who created the HTML page. Although this use of doesn't actually call up a mailto: link in most browsers, some may recognize it eventually. In the meantime, it gives people who view our source code the e-mail address of the author, as in the following example:

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Review Questions 1. What tag tells where a link starts? a. b. c. d. 2. Is it possible to make a link within the current page? a. No b. Yes 3. Which a. b. c. d.

is NOT a predefined target for links? _blank _daughter _parent _top

4. Imagelinks can show a text label if you add which property? a. str b. alt c. label d. tooltip 5. To set the font for a single link, where do you add the tags? a. Outside the and tags b. Anywhere in the tag c. Inside the and tags

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Summary A hyperlink allows us to navigate between different pages or within same page. Anchor element ‘’ can be used to create hypertext and hypermedia links. Section links can be created within same document by using ‘name’ attribute to the tag. The ‘name’ text is case-sensitive and that the associated HREF text should use the same case for all letters.

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HTML, DHTML & JavaScript Chapter 8: Clickable Image Maps and Graphical interfaces

Objectives • •

Adding Image in web Use Imagemap for better interactivity

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This chapter takes creating a graphical interface to our Web site one step further. With image maps, we can create an entire interface for our Web pages and sites that rival the interfaces of popular multimedia games, graphical operating environments, and interactive kiosks.

Image Maps Defined The map part of image map conjures up two separate images. First, image maps on Web sites often act like road maps for the Web site, adding interface elements that make it easier to get around on the Web site. Second, the word map also suggests the way that image maps are created. Image maps begin life as normal graphics (usually in GIF or JPEG format), designed with the Web in mind. Then another program is used to map hot zones (clickable areas) on top of the graphics. When put in place on a Web page, an image map allows users to access different HTML pages by clicking different parts of the graphic. Because each hot zone has an associated URL, and because each hot zone corresponds to part of the graphic, manoeuvrings about a Web site becomes more interesting, graphical, and interactive. Example: The L&T Infotech - SPLICEM Web Site L&T Infotech offers a very interesting example of an image map on the main page of its SPLICEM Web site. When the page loads in your browser, you'll see the interface, which looks a little like a some professionals are playing their roles on dirrerent platforms, on-screen. This example isn't terribly structured, but it allows you to play with the image map interface. You may already have a good deal of experience with such interfaces, especially if you've spent a lot of time on the Web. By simply pointing at part of the graphic, you may be able to bring up a URL in the status bar at the bottom of your browser bar. This bar shows you where the various hot zones for the image map are and at what coordinates your mouse pointer appears.

The image map interface at L&T Infotech’s SPLICEM Web site

Check out one more things. If the image map fills your screen, scroll down in your browser window so that you can see what's below the interface on SPLICEM's Web page. The text directly below the interface almost exactly mirrors the hyperlink options you have with the image map, because image maps, unlike click able graphics, don't offer an ALT statement for the various hot zones. So you have to include additional links to cater to your users of no graphical browsers. Training & Development Division

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Understanding How Image Maps Work Creating an image map involves three steps: creating the graphic, mapping the graphic for hot zones, and placing the correct information (along with the correct programs) on the Web server itself. This section discusses the Web server; the next section talks about defining hot zones. To offer your users the option of using image maps, you must have a special map server program running on your Web server. For UNIX-based servers, this program will most often be NCSA Image map; other platforms have their own map server programs. The Map Server Program When a user clicks an image map on a Web page, the browser determines the coordinates of the graphic (in pixels) that describes where the user clicked. The browser then passes these numbers to the map server program, along with the name of the file that contains the URLs that correspond to these coordinates. NCSA Image map, then, simply accepts the coordinates and looks them up in the database file that defines the hot zones for that image map. When NCSA Image map finds those coordinates and their associated URL, it sends a "connect to URL" command (just as a hypertext link does) that causes your browser to load the appropriate HTML document.

Defining Your Image Map Hot Zones As a designer, you are responsible for doing two things in the hot zone definition process. First, you need to define the hot zones to create the image map-that is, you need to decide what URL the coordinates will correspond to when the image map is clicked. Second, you need to create the map definition file that makes the hot zone information available to the Web server. For Windows and Macintosh users, luckily, programs that do both are available. MapEdit for Microsoft Windows and X-Windows Available for all flavours of Windows (Windows 95, Windows 3.1, and Windows NT) and for most types of UNIX, MapEdit is a powerful program that allows you to graphically define the hot zones for your image maps. You can access and download the latest version of this program via the MapEdit Web site (http://www.boutell.com/mapedit/). When you have the program installed and you double-click its icon to start it, follow these steps to define your map: Choose File, Open/Create from the MapEdit menu. The Open/Create Map dialog box appears. In the Open/Create Map dialog box, enter the name of the map definition file you want to create and the name of the graphic file you want to use for your map. You should also use the radio buttons to determine whether you'll use CERN or NCSA map definitions. (Consult your map server software or ISP if you're not sure whether to use CERN or NCSA.) Click the OK button. The Creating New Map File dialog box appears. In this dialog box, click yes. After a moment, MapEdit displays your image file. To create a new hot zone, choose the shape from the Tools menu; then click one time for each point required for the shape. For a rectangle, click once to start the rectangle and then click where you'd like the opposite corner of the triangle to appear. For a circle, click for the middle, and then drag out the circle and click when you've got the right radius. The triangle tool is actually a "polygon" tool, so click for each point in the polygon. Then, right-click at the last point (to connect your last point to the first point and complete the shape). When the shape is created, the Object URL dialog box appears (see below fig). Enter the URL that you want to associate with your new hot zone. (You also can enter comments, if you want.) Then click OK to continue. Add more shapes by following steps 4 and 5 until you finish mapping your graphic. Choose File, Save. Now you have a .MAP file for your image map.

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Associating an URL with the hot zone

Tip: By choosing File, Edit Default URL, you can determine whether your image map includes a default URL for clicks outside your hot zones. Example: MapEdit and a Simple Button Bar In this example, you use MapEdit to create a simple button bar-a little like the menu bar that you created with click able graphics in Chapter 11, except for the fact that this one is an image map. Start by drawing an appropriate graphic in a graphics application and saving it as a GIF file. For this example, name the file testbar.gif. Then follow these steps: 1. Open MapEdit, and choose File, Open/Create. The Open/Create Map dialog box appears. 2. In this dialog box, enter testbar.map for the map file and testbar.gif for the graphics file. (If you saved the GIF file in a different directory, use the Browse button to find and load it.) 3. When the graphic loads, pull down the Tools menu and make sure that Rect is selected. 4. Draw rectangles for the buttons, providing an appropriate URL for each button. For this example (four buttons in all), use the following URLs: http://www.Dreamcorp.com/index.html http://www.Dreamcorp.com/product.html http://www.Dreamcorp.com/service.html http://www.Dreamcorp.com/help.html 5. Choose File, Edit Default URL. The Default URL dialog box appears. 6. Enter the following URL: http://www.Dreamcorp.com/error.html 7. Choose File, Save. 8. Choose File, _Quit. Training & Development Division

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We've created your map definition file. To look at the file, open Notepad (or a similar text editor), and load the file testbar.map into it. The file should look something like figure below (although the coordinates are bound to be slightly different).

A successful map definition file created in MapEdit

WebMap for Macintosh If you're a Macintosh user, you can use a program called WebMap, which is similar to MapEdit. You can download WebMap from http://www.city.net/cnx/software/webmap.html. Install the program; then double-click its icon to start it. To create an image map in WebMap, follow these steps: •

Choose File, Open.

•

In the Open dialog box, select the graphic that you want to use for your map and the name of the map definition file that you want to create.

•

Click the OK button. After a moment, MapEdit displays your image file.

•

To create a new hot zone, choose the shape from the floating tool palette, and drag to create a hot zone. For a rectangle, circle, or oval, click and hold the mouse in the top left corner of your shape, drag the mouse to make the shape the desired size, and then release the mouse button. To create a polygon, choose the polygon shape from the tool palette and then click once on the graphic for each point in your polygon. To complete the shape, click once on the first point you created.

•

When the shape is created, enter the URL in the space provided above the graphic file You can use the pointer tool (the one that looks like a mouse pointer) to select different shapes that you've created and then edit their URLs.

•

To create a default URL, use the pointer tool to click the graphic background (not a shape). Default URL should appear in the comment window. Then enter the default URL in the URL text box.

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Using WebMap to create hot zones To create your map definition file, pull down the File menu and choose Export as Text. In the resulting dialog box, you can name your map file and save it in CERN or NCSA format. Now you're free to save the graphic and quit the program.

Adding Image Maps to Your Web Page After you create your image map and your map definition file, you're ready to add a link for your image map to your HTML page. You can accomplish this task in a couple of ways, depending on your Web server. In essence, though, the only major difference between an image map and a clickable image is a new attribute for the tag: ISMAP. Image maps follow this format: Note: It's perfectly acceptable to add other tag attributes (such as ALT) to your image map definition. Using the ISMAP attribute doesn't do much for you unless the image map is also a hyperlink, so the following code is everything that you need to add an image map to your Web page: Our next step is to figure out what to use as the URL in this hyperlink. The Image Map URL The URL that you're interested in accessing isn't a particular Web page, because using an URL to a particular Web page would defeat the image map concept; the link would act like a regular clickable graphic. Instead, you want the URL to access the map definition file. You'll have to ask your ISP (or figure out for yourself) where on the server the map file is stored. Some Web servers allow you to store the map definition file anywhere on the server; the servers are smart enough to figure out that you're accessing a map definition file and take care of the rest. In that case, you could simply store the map definition file in the current directory and access it as follows: Training & Development Division

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If you have an understanding server, this method may work for you. Other servers may require you to access a particular directory on the server, such as the /cgi-bin/ or /bin/ directory, where server scripts (mini computer programs) are stored. In such a case, something like the following examples may be the way to access the image map: If the server requires you to access one of these scripting directories, though, it may not want you to access the map definition file directly. Instead, the server will want you to use an alias. Some servers store all map information in a single database file (often called imagemap.conf) and require you to access information within the database by using an alias. You and your Web server administrator have to determine what this alias is. In that case, your link would look more like the following: Welcome to my page! Note: If you're going to test this example on an actual Web server, you need to replace the URL with the appropriate one for your Web site (and add the type of link to your map info file that's required for your server). Also, use the real name of the mapped GIF file in the tag. Save the HTML file and then load it in a graphical browser. If your graphic came up, chances are that you set the tag correctly. Notice that many browsers do not display a coloured link border around the graphic, because the graphic is now considered to be an image map. Before clicking any of the hot zones, move your mouse pointer around on the image map graphic. If you have a status bar at the bottom of your browser window, you may notice that the link keeps changing (see fig. below). Along with the URL of your map definition file, you should be seeing the current coordinates of your pointer. All this information is sent to the map server to help it figure out what region you clicked. (If you're testing this image map from your local drive, the status bar test is the only part of the example that will work.)

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An example image map, showing the URL and the coordinates that it will access if clicked

Now, if you are testing your image map on the Web server, go ahead and click the map to make sure that all the links work. If you're viewing the image map locally, turn off the graphics-loading option in your browser, and reload the page. You should notice that there's now no way to access the hyperlinks in the image map-that's why you also need text links for your image map pages.

Image Map Design Tips This chapter has covered creating and linking an image map to your Web page fairly thoroughly. Image maps are a bit of a departure from standard text-markup HTML, however, so you should learn a little bit of design theory and Web-related netiquette before you leave this chapter. Please try to keep some of the following suggestions in mind when you add image maps to your Web pages: •

Use image maps sparingly. The best way to use an image map is as a clickable menu bar or some other easy-to-recognize interface element. The point isn't really to see how graphical you can make your Web pages-just how intuitive.

•

Remember that image maps are usually little more than big graphics files. Ultimately, the key to graphics on the Web is keeping them small. Even if your image map is incredibly attractive, users will be annoyed if they have to wait many minutes for their four possible choices to download to their browsers. Use all the tips in Chapter 9 to keep your graphic as small as possible, and use image maps only to enhance usability.

•

Image maps require redundant text links. Unless you plan to leave out everyone who can't view your graphics, you need to create text links that do everything that your image map does. Remember that with clickable graphics, the ALT attribute takes care of the problem. The ALT attribute doesn't work for image maps, because a single image map graphic can have many links, so you need to create an identical text link on your page for every hot zone link in your image map.

•

Stick to normal shapes whenever possible. You should try to be conservative with your image maps (see fig. below). A graphic that looks as though it has rectangular buttons should function as though it has rectangular buttons. In other words, make your hot zones correspond logically to the image map graphics. Random hot zones randomly annoy users.

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Some sites make it their business to use image maps that break the rules. This one doesn't

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Review Questions 1. Defining clickable sub-areas on an image is called? a. Multiple linking b. Image Linking c. Image mapping d. subLinks 2. From the options below which are valid shapes for hotspots on images? a. Polygon, rectangle and circle b. Box, cube and line c. Big and small d. There is only one shape, oval 3. In the image where we are going to use Image-Map we have to use _____ attribute to specify which map we are using. a. usegraph b. usemap c. src d. fileName

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Summary An image map allows us to access different HTML pages by clicking different parts of the graphical image. To work with image map we have to map the graphic for hot zones. Three shapes i.e. polygon, rectangle and circle can be used to define the hot zones.

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HTML, DHTML & JavaScript Chapter 9: HTML Forms

Objectives • • •

Explain Web form and it’s use Form Elements, it’s attributes Formatting of web form

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The next set of HTML tags is designed to allow you to enhance the interactivity of Web pages by increasing ability to request information from users. Using the forms tags, we can ask users to enter text information, choose from menus, mark checkboxes, make choices from radio buttons, and then send that information to the Web server for processing.

Using Forms and Form-Capable Browsers Although the forms tags are a part of the HTML 3.0 standard, it's important to recognize that not all browsers are capable of viewing them-especially older browsers and text-based browsers. Users need to have forms-aware browsers, like the current versions of NCSA Mosaic, Netscape Navigator, and Microsoft Internet Explorer, among others. Generally, other browsers will simply ignore the forms commands if they can't deal with them. Tip: It's a good idea to let your users know that they're about to jump to a form-based page whenever possible. Forms pages are a waste of time for users of older browsers that don't support them. The idea behind a Web form is simple-it allows us to accept information or answers from our users with varying levels of guidance. Users can be asked to type answers, choose their answers from a list of possibilities you create, or even be limited to choosing one answer from a number of options that you specify. That data is then passed on to the Web server, which hands it to a script, or small program, designed to act on the data and (in most cases) create an HTML page in response. In order to deal with forms data then, you need to understand a little something about scripting, or programming, for a Web server-or know someone who does. Note: Most Web server scripts are written in Perl, C, or UNIX shell scripts. If your Web server is DOS, Windows, or Mac based, however, you may have other options. Some DOS Web servers allow you to script in the DOS batch language, while some Windows servers can accept Visual Basic scripts (not to be confused with Microsoft's new Visual Basic Script language). Mac Web servers generally allow for AppleScript or Frontier scripting.

Creating the Form In an HTML document, forms are set between the container tags. The form container works as follows: ...form data... Notice that the tag takes two attributes: METHOD and ACTION. The METHOD attribute accepts either POST or GET as its value. POST is by far the more popular, as it allows for a greater amount of data to be sent. GET is a little easier for Web programmers to deal with, and is best used with single responses, like a single textbox. The second attribute is ACTION, which simply accepts the URL for the script that will process the data from your form. Most often the script is stored in a directory called bin/ or cgi-bin/ located on your Web server. An example of the tag then, would be the following: As with any HTML container tag, this implementation of the tag has actually created a complete form (just like and is a complete paragraph). Unfortunately, our complete form doesn't do anything yet, so that's somewhat academic. Note I: You can't nest forms within one another. You need to add the end tag for the first form before creating another one in the same document. Generally, browsers will ignore any new Training & Development Division

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occurrences of the tag, since the purpose of the tag is to tell the browser how to submit data to the server, and different parts of the form can't be submitted in different ways. Note II: Nearly all-graphical browsers have a View Source command. Look in the Edit menu for this command or a command with a similar name. The HTML source of the current Web document will then be displayed or saved as a text file. Notice a couple of things here. The tag at lntinfotech is using the ACTION and METHOD attributes that were discussed. ACTION is accessing a script called loginPage.html found in the cgi-bin/ directory of the Web server. The METHOD used is POST.

Text Fields and Attributes One of the more common uses for forms is to accept multiple lines of text from a user, perhaps for feedback, bug reports, or other uses. To do this, use the tag within your form. You can set this tag to control the number of rows and columns it displays, although it will generally accept as many characters as the user desires to enter. It takes the following form: default text It may surprise you to find that is a container tag, since it just puts a box for typing on the page. What's contained in the tag is the default text-so you can guide your users by letting them know what you'd like entered there. For instance: Enter comments about this Web site. Good or Bad. The default text appears in the textbox just as typed. Notice in figure below that text inside the tag works like formatted text. Any returns or spaces you add to the text are displayed in the browser window. In fact, notice that by hitting Return after the opening tag, I'm inserting a blank line at the top of the textarea (in many browsers).

The tag in action

The NAME attribute is a variable name for this string of text. It gets passed on to your processing script on the Web server. ROWS and COLS can accept different numbers to change the size of the textarea box, but you should take care that the majority of browsers can see the entire box on-screen. It's best to limit COLS to 80 and ROWS to something like 24 (the typical size for a text-based computer screen). But it's up to you. will also accept one other attribute: WRAP. WRAP can be set to OFF (which is the default if WRAP is not included), VIRTUAL, or PHYSICAL. Setting wrap to PHYSICAL forces the browser to include actual line breaks in the text when sending it to the Web server. VIRTUAL makes the textbox seem to offer line wrap, but sends a continuous stream of words to the Web server (unless the user has entered returns on his or her own).

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Example: Web-based Feedback Form We have mentioned before that is commonly used to gather feedback from your Web users. To create a small form to do just that, save your default template as a new HTML document and enter the following: Feedback Form Please take a moment to tell us what you thought of the Web site. Your Feedback is appreciated! Enter your comments below: Dear BigCorp: You can see how this looks in figure below. Notice in the example that some descriptive text is enclosed inside the tag, but outside of the tag. This is completely legal-it just lets you explain what the purpose of the textarea is.

Sample textarea HTML form

You may have realized that there's something lacking in this sample form. There's no way to submit the user's entry! You'll get to that in the next section, when I discuss this next tag for form entry.

The Tag Our next tag for HTML forms give you the opportunity to be a bit more picky about the type of input you're going to accept from the user. The tag follows the following format: Now, technically, the only required attributes are TYPE and NAME. Some other "types" of the input tag will also accept the attribute VALUE. But first, let's look at the different types of .

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Note: By the way, notice that is an empty tag. There's no element. Text The first possible value for the TYPE attribute is TEXT, which creates a single-line textbox of a length you choose. Notice that the length of the box and the maximum length entered by the user can be set separately. It's possible to have a box longer (or, more often, shorter) than the maximum number of characters you allow to be entered. Here's an example of a textbox: Last name: When appropriately entered between tags, this yields a box similar to figure below. If desired, the attribute VALUE can be used to give the textbox a default entry, as in the following example: Type of Computer:

Using the TEXT option with the TYPE attribute

PASSWORD The PASSWORD option is nearly identical to the TEXT option except that it responds to typed letters with bullet points or a similar scheme (chosen by the browser) to keep the words from being read. A sample password box could be the following: Enter Password: When characters are typed into this textbox, they are shown on the screen as in figure below

PASSWORD hides text from people looking over your user's shoulder

Recognize that the text is still stored as the text typed by the user-not as bullet points or similar characters. CHECKBOX This value for TYPE allows you to create a checkbox-style interface for your form. This is best used when there are two possible values for a given choice-and no others. You can also determine whether or not a checkbox will already be checked (so that it must be unchecked by the user, if desired), by using the attribute CHECKED. Here's an example of adding checkboxes to a form: Type of computer(s) you own: Pentium 486-Series PC Macintosh In this example, it's possible to check as many of the options as are presented. CHECKBOX evaluates each item separately from any others. Figure below illustrates how CHECKBOX is displayed in a browser.

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Notice that Pentium is prechecked

RADIO Like CHECKBOX, RADIO is designed to offer your user a choice from pre-determined options. Unlike CHECKBOX, however, RADIO is also designed to accept only one response from among its options. RADIO uses the same attributes and basic format as CHECKBOX. RADIO requires that you use the VALUE attribute, and that the NAME attribute be the same for all of tags that are intended for the same group. VALUE, on the other hand, should be different for each choice. For instance, look at the following example: Choose the computer type you use most often: Other

With RADIO, it's important to assign a default value, since it's possible that the user will simply skip the entry altogether. While the user can't check more than one, he or she can check none. So choose the most common value and set it as CHECKED, just so that the form-processing script doesn't have trouble. Note: Of course, if you want to give your user the option of choosing none, then you can leave off the CHECKED attribute. It's more complete and obvious for the user, however, to include another radio button with a VALUE of none, and make it the CHECKED choice. HIDDEN This type technically isn't "input" at all. Rather, it's designed to pass some sort of value along to the Web server and script. It's generally used to send a keyword, validation number, or some other kind of string to the script so that the script knows it's being accessed by a valid (or just a particular) Web page. The tag takes the attributes NAME and VALUE. Note: This isn't really terribly covert (hidden), since an intrepid user could simply choose View Source to see the value of the hidden field. It's more useful from a programmer's standpoint. For instance, on a large Web site, the hidden value might tell a multi-purpose script which particular form (among many) is sending the data, so the script knows how to process the data. RESET The tag has built into it the ability to clear an HTML form. RESET simply creates a push button (named with the VALUE string) that resets all of the elements in that particular FORM to their default values (erasing anything that the user has entered). An example would be the following: With a VALUE statement, you could enter the following: The results are shown in figure

Default and VALUE-attributed Reset buttons Training & Development Division

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SUBMIT The tag also has a type that automatically submits the data that's been entered into the HTML form. The SUBMIT type accepts only the attribute VALUE, which can be used to rename the button. Otherwise, the only purpose of the Submit button is to send off all the other form information that's been entered by your user. See the following two examples

Creating a Submit button

You can use just about anything you want for the VALUE, although it's best to remember that really small words, like OK, don't look great as buttons. To make a button larger, enter the VALUE with spaces on either end, like in the following: Example: A More Complete Form Along with all the other types, now you've finally got a way to submit data. So, let's create a more involved form that includes some of these examples-a subscription form. Save your HTML template to create a new document. Then, enter something similar to Listing below. Creating a Complete Form Subscribe to CorpWorld Interested in receiving daily email updates of all the latest exploits of BigCorp? Well, now you can. And, best of all, it's free! Just fill out this form and submit it by clicking the "Send it In" button. We'll put you on our mailing list, and you'll receive your first email in 3-5 days. Please complete all of the following: First Name: Last Name: Business: We must have a correct email address to send you the newsletter: Email: How did you hear about BigCorp's email letter? Here on the Web In a magazine Newspaper story Other Would you care to be on our regular mailing list? Yes, I love junk mail Notice that, for text type boxes, the MAXLENGTH is one less than the size of the box. This tends to look a little better, but choosing the size is up to you. Figure below shows how it looks on a Web page.

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The complete form in MS Internet Explorer

Creating Pop-Up and Scrolling Menus The last types of input that you can offer to users of your Web page revolve around the tag, which can be used to create different types of pop-up and scrolling menus. This is another element designed specifically for allowing users to make a choice-they can't enter their own text. The tag requires a NAME attribute and allows you to decide how many options to display at once with the SIZE attribute. Using Also notice that, like , is a container tag. Options are placed between the two tags, each with a particular VALUE that gets associated with 's NAME attribute when chosen. The following is the basic format: Menu text Menu text ... The attribute SELECTED is simply designed to show which value will be the default in the menu listing. Value can be anything you want to pass on to the Web server and associated script for processing. An example might be: Choose your favourite food: Italian TexMex Training & Development Division

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SteakHouse Chinese You can also use the SIZE attribute to decide to display the menu in its entirety, by simply changing the first line of the example to the following: Both examples are shown in figure below.

Two menus-a pop-up and a fixed

In the first example, selecting the menu item with the mouse causes the menu to pop-up on the page. The user can then select from the choices. In the second example, it's necessary to click the desired item. Allowing More than One Selection One more attribute for the tag allows the user to select more than one option from the menu. Using the MULTIPLE attribute forces the menu to display in its entirety, regardless of the SIZE attribute. An example might be the following: (the result appears in figure below )

A menu can allow multiple choices

What type of cars does your family own (select as many as apply)? Sedan Coupe Minivan Conversion Van Stationwagon SUV (4x4) Other Truck

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Review Questions 1. What is a. b. c. d.

a field that allow the visitor to enter information called _____. Meta tags Form fields Data field Meta fields

2. Which attribute specify where to send a form? a. Method b. Action c. Input d. name 3. Which of the following is not a form field? a. Tool box b. Radio button c. Reset button d. Password field 4. The value setting of a text field defines ____? a. The length of the field b. If the value entered is a proper value c. What will appear in the field as the default value d. None from the options 5. Which field can hold information that does not show? a. Hidden field b. Frame field c. Text field d. Unshown fields

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Summary Interactivity of Web pages can be increased by using ability to request information from users. With the help of ‘FORM’ tag, we can ask users to enter text information, choose options from menus, mark checkboxes, and make choices from radio buttons and to send the information to the Web Server for processing. Form controls are set between the container tags. tag takes two attributes: METHOD and ACTION which will tell to Server how to send the data and which page to be displayed after submitting the data. We can't nest forms within one another. By using Input Tag we can design various types of input controls like textbox, password field, text area, buttons, hidden field etc.

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HTML, DHTML & JavaScript Chapter 10: Images, Multimedia Objects and Background Graphics

Objectives • •

Explain relationship of HTML and multimedia To include multimedia object in web page

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Inserting Multimedia Objects One of the latest HTML 4.0 (or, at least, beyond HTML 3.0) initiatives has been the addition of a tag called the tag, which expands on the role of the tag by allowing various different multimedia types to be displayed inline. As the bandwidth of connections to the Internet grows, and the technology for inline multimedia grows with it, more and more Web viewers will be capable of viewing inline animations, presentation graphics, movies, and more. As of this writing, very few browsers support the tag. Unlike some other HTML initiatives, however, this specification has been written with much more involvement from industry leaders like Microsoft, Netscape, Spyglass, and Sun. The Tag This is not exactly the easiest tag to get your arms around. Like tables, the tag is a container for other tags that help define the element. But, somewhat unlike tables, most of those contained tags don't actually display anything. Let's take a look at a typical container: Other Insert tags... Already, there are a couple of things you're required to know. You need to know the filename of the multimedia file or the appropriate URL if it's not in the current directory. You also need to know the MIME-style "type" of the data file. MIME-Style Data Types MIME (Multipurpose Internet Mail Extensions) data types are simply the standardized way that certain Internet programs can identify the type of ASCII and non-ASCII files that are being transferred to a client application. A very common example of this is the text/html MIME type. The tag (and HTML in general) is not limited to the official MIME categories and types, hence we'll call them MIME-style data types. For the purposes of the tag, this is just a more reliable way to tell a Web browser what type of multimedia file to expect more reliable, that is, than just the file's extension. Some common MIME-style data types appear in Table below. These and others are all useful for the tag. Type of File

MIME Equivalent

GIF

image/gif

JPEG

image/jpeg

AIFF sound

audio/aiff

WAV sound

audio/x-wav

QuickTime video

video/quicktime

AVI video

application/avi

Real Audio

application/x-pnrealaudio

Macromedia Director

application/x-director

OLE object

application/x-oleobject Some MIME-Style Data Types for the Tag

MIME-style data types for newer multimedia formats (especially vendor-specific ones like Macromedia Director) will generally be in the form of application/x-data type. More often than not, these are the types you'll use for the tag, since these are the data types used for browser plug-ins.

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's Attributes Aside from DATA and TYPE, can also accept the attributes ALIGN, WIDTH, HEIGHT, and BORDER. Its format is as follows: ALIGN works much as it does with . The values possible for ALIGN are shown in Table below. Notice that some of these values (LEFT, CENTER, MIDDLE) cause to act as a separate object, while the others assume the inserted multimedia object is supposed to be inline with the text of the document. You may recall that this is almost identical to what you learned about at the beginning of this chapter. Value

Acts as

How Object is Aligned

LEFT

Object

With left border and allows text wrap

RIGHT

Object

With right border and allows text wrap

CENTER

Object

Between browser borders and allows text wrap

TEXTTOP

Inline

Top vertically aligned with top of text's font

MIDDLE

Inline

Middle vertically aligned with middle of text's font

BASELINE

Inline

Bottom vertically baseline of text

TEXTBOTTOM

Inline

Bottom vertically aligned with lowest point in text

aligned

with

Values for the Attribute

WIDTH and HEIGHT accept numbers and unit suffixes (like px for pixels and in for inches). These two attributes are used to define the size of the object for faster downloading. Some browsers will also resize objects according to these attributes, so that you might expand a smaller inline movie's object with WIDTH and HEIGHT, for instance, to save on downloading time. WIDTH and HEIGHT take the following format: The last parameter is BORDER, which has a default value of 1. The border will generally only appear when the entire object in enclosed in an anchor tag, as in the following example:

Using and with Two of the most common tags you'll want to use with the tag are the and tags. The tag is used just as it has been elsewhere except it's only displayed when the browser isn't able to deal with the type of multimedia file that the tag is trying to send. For instance, if you were sending a Macromedia Director multimedia file from your Web pages, but the receiving browser wasn't able to deal with it, the tag would substitute the you'd specified instead.

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The tag is used to offer additional parameters to the tag information like how many times to play a movie clip. The tag takes elements NAME and VALUE, which work a little like they do for certain table tags. Unfortunately, each different type of multimedia file will require different NAME and VALUE values, so you'll have to seek those out from the creator of the particular object type you want to send. Here's an example of the tag: The tag is used within an definition in the same way that it is used elsewhere, except that the ALIGN attribute isn't really necessary since the will only be used to directly replace the inserted multimedia object. You can add the like this: Clearly, you'll often want the graphic to at least represent the multimedia file that can't be displayed (see fig. below). Or, perhaps, you could cause a graphic to load that tells the user that he or she is missing out on something better.

The tag in action.

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Review Questions 1. The background image will scroll when the user scrolls down the page, unless you add which property to the tag? a. bgproperties="fixed" b. bgproperties="stationary" c. bgproperties="holdstill" d. background-image=”stable” 2. Why should you specify a background color if you are using an image for the actual background of your page? a. The background color will be shown until the image loads b. In case the image doesnt fit right c. So the text shows up better 3. _____ tag can be used to add multimedia file objects. a. b. c. d.

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Summary Various multimedia objects can be inserted to add interactivity and to give better look to web pages. tag can be used to add multimedia object to a web page. The tag is used to offer additional parameters to the tag information.

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HTML, DHTML & JavaScript Chapter 11: Adding Tables to your Documents

Objectives • • •

Understanding how to create tables Using Captions, Table Headers and Table Data tags To know alignments of tables

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Creating a Table Tables work a lot like HTML list tags; in that you must use the table container tag to hold together a group of tags that define each individual row. The main container is the tag, which uses enclosing tags for table rows () and table data (). Most tables will also use an element for table headers (), which is generally used as the title text for rows and columns. Tables take the following format: Caption text for table column1column2column3 row1data1row1data2row1data3 row2data1row2data2row2data3 ... An example of a table using this format might be the following: Team Members for 3-Person Basketball Blue TeamRed TeamGreen Team Mike R.Leslie M.Rick G. Julie M.Walter R.Dale W. Bill H.Jenny Q.Fred B. After you work with HTML list containers, it's fairly easy to make the jump to creating tables in HTML. You can see how this table looks in figure below.

A simple table in HTML

The Tag The tag is actually a rather complex creature, at least insofar as it can accept many different attributes. Some of the attributes are more useful than others, so let's look at the most useful of them as they currently stand: •

ALIGN. The ALIGN attribute is used to determine where the chart will appear relative to the browser window. Valid values are ALIGN=LEFT and ALIGN=RIGHT. As an added bonus, text will wrap around the table (if it's narrow enough) when the ALIGN=LEFT or ALIGN=RIGHT attributes are used.

•

WIDTH. The WIDTH attribute sets the relative or absolute width of your table in the browser window. Values can be either percentages, as in WIDTH="50%", or absolute values. With absolute values, you must also include a suffix that defines the units used, as in px for pixels or in for inches (e.g., WIDTH="3.5in"). Absolute values for table widths are discouraged, though.

•

COLS. The COLS attribute specifies the number of columns in your table, allowing the browser to draw the table as it downloads.

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•

BORDER. The BORDER attribute defines the width of the border surrounding the table. Default value is 1 (pixel).

•

CELLSPACING. The CELLSPACING attribute tells the browser how much space to include between the walls of the table and between individual cells. (Value is a number in pixels.)

•

CELLPADDING. The CELLPADDING attribute tells the browser how much space to give data elements away from the walls of the cell. (Value is a number in pixels.)

It is definitely not necessary to use all of these attributes for your table-in fact, the simple table example earlier didn't use any of them. Often, however, they will come in handy. Example: Playing with Table Attributes This is another fairly freeform example. Let's look at the difference between a plain table and a table embellished with a few attributes. Insert Listing below in a new HTML document. Creating a Plain Table BigCorp's Computer Systems We use only the highest quality components and software for all of our Wintel computer systems. Plus, if you don't see a configuration you like, call (or email) and let us know. We'll custom build to please! BigCorp's Computer Systems and Specifications System 486System 586System 686 486DX2-66 CPU120 MHZ AMD586200 Mhz Pentium Pro 8 MB RAM16 MB RAM16 MB RAM 500 MB HD1 GB HD1.4 GB HD 14.4 Modem28.8 Modem28.8 Modem desktop caseminitower casetower case DOS/Win 3.1Windows 95Windows NT 4.0 Last time we tried a simple table, it communicated its data well. But this one is fairly ineffective, with everything lined up so poorly. Using just the attributes only mentioned, though, you can change this table so that it looks better to the user and is easier to read. All that needs to change is the first tag: That makes for a much nicer looking table, complete with borders and lines for cells, and a comfortable amount of spacing to separate cell data elements from one another (see figure below).

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Look how nice the table looks with spacing and borders The rest of this example is up to you. Play with CELLSPACING and CELLPADDING without a border, for instance, or increase all values out of proportion. See the range of what's available, to help you choose how to format your tables in the future.

Captions, Table Headers, and Table Data To round out your tables, you have the other basic tags to examine. You've already successfully used , , and , but each has its own attributes and abilities that you need to know about. The tag is a container for reasons that may be obvious-it allows you to nest other HTML tags within the description. For instance: Table 3.1 from the book Life in El Salvador Just about any sort of markup tags are possible inside the tags, although some-like list tagswouldn't make much sense. The tag has one attribute, ALIGN. ALIGN="TOP" and ALIGN="BOTTOM" are encouraged. By default, text is also aligned to center (horizontally). By TOP and BOTTOM, I'm referring to the entire table; the caption will default to the top of the table if not otherwise specified. To align the caption to BOTTOM, for instance, enter the following: Table of Common Foods The tag is commonly the first tag just inside the tag (although this placement is not required). Regardless of where you place the tag, however, you must use ALIGN to force it to the bottom of the table. Otherwise, it will appear at the top, according to its default. Let's create an entire table and use the ALIGN attribute to the tag to force the caption to the bottom, like this: Training & Development Division

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Favourite Ice Cream Flavours Data from the New Jersey Times DateChocolateVanilla 197050%50% 198076%24% 199040%60% When the browser interprets this table, it should place the caption at the bottom of the table, centered horizontally (see fig. below).

You can align the caption to BOTTOM.

Table Rows Table rows () can accept one attribute you should concern yourself with-ALIGN. The ALIGN attribute is used to determine how text will appear (horizontally) in each of the rows data cells. For instance: 199040%60%

Here, I've added the ALIGN attribute (with a value of CENTER) to the rows in the previous example. Notice now that all cells center data horizontally (see fig. below). This ALIGN attribute can also accept LEFT and RIGHT.

This uses the ALIGN attribute with

Note: HTML 4.0 also supports another useful attribute, VALIGN, which accepts the values TOP, BOTTOM, and CENTER. Using this attribute, you can choose to align cells vertically as well as Training & Development Division

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horizontally. Until they support VALIGN, non-HTML 4.0 browsers should ignore VALIGN. Unfortunately, those are currently the most popular browsers! Table Data and Rows You've already used the and tags to include headers and data in your tables. You may have noticed that, essentially, the only difference between the two is that emphasizes (boldfaces) the text and does not. Now, technically, the is a tag that the browser interprets as a header and thus displays text in a way that's distinct from the tag. In practice, that generally means it's turned bold. Aside from accepting nearly any type of HTML mark-up tags within them, both tags can accept four attributes (in most HTML versions). These are ALIGN, VALIGN, COLSPAN, and ROWSPAN. If you were to add all of these attributes, a typical (or ) tag would be formatted like the following: ALIGN is used to align the data within the cell horizontally, accepting values of LEFT, RIGHT, and CENTER. Note that ALIGN is redundant when used with the ALIGN attribute of , unless it is used to override the setting. VALIGN is used to align the data vertically within cells. Possible values are TOP, BOTTOM, and CENTER. COLSPAN and ROWSPAN are used to force a cell to span more than one column or row, respectively. An example of this might be: StudentTest 1Test 2Average Mike M. 10075N/A Susan T.8095 Bill Y.Dropped Course Viewed in a browser, the table looks like figure below

Using COLSPAN and ROWSPAN in a table

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Review Questions 1. To add a. b. c. d.

rows to your tables use which tags? and and and and

2. To set the color for table borders use __________ . a. bgcolor=#003300 b. bgimage=#003300 c. bordercolor=#003300 d. border=#003300 3. Increasing the cellpadding value will make what change? a. Increase the softness of your site b. Increase the distance between cell and content c. Increase the space between cells d. Merges two or more cells depends on settings 4. Which a. b. c. d.

property tells how many rows a cell should span? colspan=n rowspan=n Both rowspan=n and colspan=n None from the options

5. What tag is used to add columns to tables? a. b. c. d.

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Summary Tables help us to align contents and to keep data in tabular format. tag is used to create table structure on web pages. Attributes like border, cellspacing, cellpadding can be used to add impact of tables. tag is used to define table rows and is used to define data in table cells. Incase if we require to merge two or more cell or columns then we can use either rowspan or colspan attributes inside or tags.

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HTML, DHTML & JavaScript Chapter 12: Frames

Objectives • • • •

Apply frames for formatting Explain attributes of frames Discuss use of Noframe in HTML To Target frame window

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One of the most exciting Netscape-only additions to HTML recently has been the frames specification. Although submitted to the W3C, frames, for now, remain almost exclusively Netscape-only. Frames aren't overwhelmingly difficult to add to your pages, although they do require a slight shift in thought. Although they seem similar to tables at first, frames are considerably more powerful. In fact, that frames can even divide your Web page so that it is accessing more than one URL at a time.

The Idea behind Netscape Frames Netscape frames are basically another way you can create a unique interface for your Web site. By dividing the page into different parts-each of which can be updated separately there becomes a number of different interface elements you can offer. Even a simple use of the frame specification lets you add interface graphics or a corporate logo to a site, while the rest of your page scrolls beneath it (see fig. below).

A simple frames interface Using frames in this way takes you one step closer to the ideal Web interface, because it makes it as intuitive and universal as possible. Frames are ideal for the following: •

Table of Contents (TOC). By placing the TOC in a "column" on your Web page, people can click around your site or your documentation pages without being forced to constantly move "back" to the contents page. Instead, users simply click a new content level in the static frame.

•

Fixed interface elements. As mentioned previously, you can force click able graphics, logos, and other information to stay in one fixed portion of the screen, while the rest of your document scrolls in another frame.

•

Better forms and results. Frames also enable you to create a form in one frame and offer results in another frame. This is something we're beginning to see extensively with Web search pages (refer to fig. below). With the search text box always available, you're free to change search phrases or pinpoint your search more quickly, without moving back in the hierarchy of the Web pages.

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Creating Frames Probably most unique among the HTML-style tags so far is the tag. This container is required for frames-style pages-but it also replaces the tag completely on these pages. When you use frames then, you're committed to using them completely-you can't just add frames to part of your page. On a typical page, is added like this: ...HEAD markup... ...Frames and other HTML markup... The tag can accept two attributes: ROWS and COLS. Both attributes accept numerical values (size in pixels), percentages, or a combination of both. The value * can also be used to suggest that a particular row or column should take up the rest of the page. The number of values suggests the number of rows or columns you give the attribute. These attributes take the following format: An example like the following would create two rows: one 50 pixels long and another row that took up the rest of the page: (This would be useful for a page that displays a fixed map or graphic at the top.) The following example would create a Web interface with two columns: one on the leftmost 25 percent of the screen and one on the other 75 percent: This would be a good way to set up a documentation (or FAQ) site that offered contents in the first frame and actual text and examples in the second, larger frame. Each statement will work with one attribute or the other. That means you can only create a frameset with either rows or columns. In order to create rows within columns (or vice-versa), you can nest statements. For instance, the following will create a page with two columns: The first column will be divided into two rows that take up 50 percent of that column a piece. The second column will be divided into two rows, the first taking ten percent and the second taking the rest of that column. Although this doesn't display anything in and of itself, it creates logical breaks in the page that look like figure below. You'll come back to nesting tags as you develop more advanced frame interfaces in this chapter.

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The logical breaks created by nested tags

The Tag The tag is used within the container to determine what will actually appear in a particular frame. Each tag is an empty tag-and it's not unlike the tags you add to HTML lists. It's simply there, within the container, to determine what URL or name is associated with the particular frame it defines. It takes the following format: ... The SRC attribute is used to tell the frame what URL should be loaded in that frame. For instance, the following would create two frame rows-one that loaded the URL index.html at the top of the Web page and one that loaded the URL help.html at the bottom of the page (see fig. below):

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The tag assigns URLs to each frame window

By using the tag, you create what's known as a frame window. Each window corresponds to a "row" or "column" definition in the tag, but nothing is drawn or displayed until an appropriate tag is used to define each individual window. Example: A Simple Frame Document You'll essentially create the same document that was shown in the previous figure, but you should feel free to play with the numbers a bit to see how different percentages and even different attributes to changes how the page displays. Enter Listing as shown below in your text editor. Simple Frame Document Frame Example While you're at it, you also need to create some files to put in those frames. If you have some HTML documents hanging around, you can rename menu.html and help.html to any HTML file you'd like to load. For this example, any HTML document names will work (see fig. below).

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Loading separate HTML documents into a frame-based page

If you'd like to experiment further, try changing the tag in Listing 20.1 to the following: Or, change the percentages to see how that affects your layout. Attributes for Aside from SRC, the tag can SCROLLING, and NORESIZE. All of these and come back to NAME in a moment. MARGINWIDTH and MARGINHEIGHT are margins of the text and graphics within For example:

accept the attributes NAME, MARGINWIDTH, MARGINHEIGHT, but NAME are appearance-oriented. Let's deal with them first used to control the right/left margins and the top/bottom a frame, respectively. Each takes a numerical value in pixels.

This creates a five-pixel border between the contents of text.html and the frame edges. SCROLLING can accept the values yes, no, and auto and is used to determine whether or not scroll bars will appear in the frame window. The default value is auto, and this is probably the best to use in most cases. Since users have all different screen resolutions and available browser window space, even short documents will sometimes need to be scrolled. The NORESIZE attribute doesn't require a value assignment, and is used to keep the user from resizing a frame window. (Frame windows can be resized by dragging the frame with the mouse in the viewer window.) An example of SCROLLING and NORESIZE would be: The Tag This container tag is used to contain HTML mark-up intended for browsers that do not support the frames specification. Frames-capable browsers ignore text and HTML tags inside the container. All others should generally ignore the other frames tags (which they won't recognize), but display the text in between the tags. The following is an example:

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This page requires a Frames capable browser to view. If you'd prefer, you can access our HTML 3.0 compliant pages to view this information without the frames interface. Experiment with different values for the attributes and see what makes a big difference in terms of margins, scrolling, and resizing. Also, if you have access to a browser that isn't framescapable, load the page and see how the markup looks (see fig. below).

The HTML message

Targeting Frame Windows So far, you've seen that frame windows offer you the ability to load URLs independent of one another, so that you can present two (or more) different HTML pages in the same browser window. But what good is this to you? In many cases, it may be useful to offer multiple documents at once. For instance, with what you know now, you could use frames to add a button bar image map to the top of every HTML page you create. But that would get tedious-each link would have to point to a new frame document that would then load the button bar and the next document. But what if you could just leave the button bar in the top frame window and load a new document in the other window? You can do just that, if you know a little about targeting. The NAME Attribute First, you need to name your frame windows-at least, you have to name the windows you might want to change. This is accomplished with the NAME attribute to the tag, which takes the following format: This shouldn't look too foreign to you, as it's a little like the way that the NAME attribute works for links. Once the frame window has a distinct name, you can access it directly from other frame windows. An example of this is the following:

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Although you can pretty much name your frame window anything you want, there is one restriction: you can't start the name with an underscore character (_). If you do, the name will be ignored. But, there's a good reason for that. The underscore is used to signal a number of "magic" target names. You'll get to those after you learn how to target regular browser windows. Targeting Frame Windows With your frame successfully named, you're ready to target the name with a hypertext link. This is accomplished with the TARGET attribute to a typical anchor tag. It follows this format: link text The new_URL is the new document that you want to appear in the frame window. The window_name is the same name that you used to name the frame windows with the NAME attribute to the tag. An example would be the following: View Products

Advanced Targeting Other link-related tags have been updated to accept a TARGET attribute along with the anchor tag. For instance, client-side image maps have their AREA tag updated to accept a target window, so that an area defined to access a certain link loads that page into the target. This is the format: Likewise, you can add a TARGET attribute to the tag. Remember that it's the container tag that tells the browser the URL for the script that is required to process the form data. In that same tag, you can also specify a target window for the results that are received from the server. If you want users to be able to use your form repeatedly (to allow them to generate different results), you can leave both the form and the results in separate frames. This attribute takes the following format: Targets The last example you went through (Listing 20.4) would have been a great candidate for this one type of target. What if you want the majority of your links to point to a particular frame window? In the early example, you created a file called control2.html that had nothing but hypertext links. Each one of those links required a TARGET attribute that pointed to the big_window. You could have made that easier with a tag in the head of your document. Use this format: A good example of this for the previous example would be: You don't have to specify the target window in each individual anchor in an HTML document that has this tag in its head. Now all links will default to the target defined in the tag. Note: If you do use TARGET attributes, they will override the tag for that particular link. "Magic" Targets Here's why you can't name frame windows with something that starts with an underscore. The "magic" target names all start with an underscore, which signals to the browser that they should treat this link extra special. The following are some examples: •

TARGET="_blank"-The URL specified in this link will always be loaded in a new blank browser window.

•

TARGET="_self"-This is used for overriding a tag, and forcing a link to load in the same window that it's clicked in.

•

TARGET="_parent"-This causes the document to load in the current window's parent-generally, the frame window immediately proceeding in the definition. If no parent exists, it acts like "_self".

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•

TARGET="_top"-The document is loaded in the topmost frame of the current browser window.

Basically, these magic targets are designed to let you break out of the current structure in some way. Experiment with them to see how you can move around to different windows. The Elegant Frame Interface Let's use three different frame windows. One will hold a client-side graphic for your site, one will offer a "table of contents" page, and one will display the actual information for your site. You'll need a fixed window for the client-side map and two dynamic windows. One will load the parts of the table of contents, and one will load the information pages. Use listing below for the client-side map. HTML for a Client-Side Map Control Map Notice that this graphic isn't designed to change the main window. It's going to change the documents that show up in your table of contents window. Each of the TOC documents should be a simple HTML list of links that shows the branch that the users have travelled down. For instance, let's create the document serv_toc.html (see Listing below). serv_toc.html - A Sample TOC Document Service Contents Main Products Page Software Hardware Furniture Accessories

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See what we are getting here? The image map will change these controls, and then these links will change the main frame window. It gives a nice, easy interface to the whole site. Now let's create the frames page which we'll call main.html (see Listing below). The Main Frames Interface BigCorp on the Web This one doesn't take up much space. Here's what you've done. The first created two rowsone for image map and one for the rest of the page. In that bottom row, you used another to create two columns within that row. The smaller is for the table of contents pages. In the other frame window, you put all of the main HTML documents. Look at figure below to see how the whole thing looks in Netscape.

A three way interface is attractive, but it can be tough to manage

Note: For this example to work well, you may need to create some other files like index_toc.html, or rename files to work in your main window. Training & Development Division

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Review Questions 1. A file that specifies how the screen is divided into frames is called a __________ . a. frametable b. tablelink c. frameset d. 2. You can add names to each frame window using which setting? a. name b. src c. ur 3. If you don’t want the frame windows to be resizable, simply add what to the lines? a. save b. dontresize c. noresize d. notsizable 4. Adding _top to a link within a frameset does what? a. loads page in parent frame b. loads the page into the current window c. cancels all frames, loads in full browser window d. None from the options 5. Which a. b. c.

is not valid HTML?

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Summary Frames are basically another way we can create a unique interface for our Web site. Frames can be used for applications like Table of Contents (TOC), Fixed Interface elements and to make ‘Form’ look more attractive and for good form look. tag can be used to create frames. Rows and cols attributes are used to define layout of frameset. To add webpage to frameset tag is used with ‘src’ as source file name. tag is used to contain HTML markup intended for browsers that do not support the frames specification. By naming frames we can open resultant link inside particular frame window.

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HTML, DHTML & JavaScript Chapter 13: Introduction to DHTML

Objectives • • • •

Introduction to DHTML Understanding the history of DHTML Enhancing User Experience To understand components of DHTML

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Introduction DHTML is the combination of several built-in browser features in fourth generation browsers that enable a web page to be more dynamic. DHTML is NOT a scripting language (like JavaScript), but merely a browser feature- or enhancementthat gives your browser the ability to be dynamic. DHTML is a collection of features that together, enable your web page to be dynamic. I think its important now to define just what the creators of DHTML meant when they say "dynamic". "Dynamic" is defined as the ability of the browser to alter a web page's look and style after the document has loaded. Web designers are often limited by default fonts such as Helvetica, Arial and Times Roman. DHTML allows downloadable fonts. Readers will be able to see web pages the way they are designed, with text that responds to exact font, size and style. DHTML is a new tool for designers to create Web pages with special effects and animation such as flying headlines and news tickers. Designers can attach a simple script to any object on a page and the user can change the appearance of a Web page "on the fly." Prior to DHTML, designers were limited to writing complicated programs to achieve the same effects.

History of DHTML During 1960’s, IBM scientists were working on a Generalized Markup Language (GML) for describing documents and their formatting. In 1986, the International Standards Organization (ISO) adopted a version of this standard called Standard Generalized Markup Language (SGML). SGML offers a highly sophisticated system for marking up documents so that their appearance is independent of specific software applications. It is big, powerful, filled with options, and well suited for large organizations that need exacting document standards. As Internet began to grow, data increase rapidly. Unfortunately, SGML made the language unsuitable for quick easy Web publishing (Randall, 319). The straightforward text was too dull for the mass-market of the Internet. Data needs to be displayed in an interesting structure and so HTML (HyperText Markup Language) was created. HTML is a subset of SGML. SGML means Standard Generalized Mark-Up Language. A Mark-Up Language alters the presentation of the content of a document. HTML presents data in a browser window in a multitude of shapes, sizes, colors, and provides extra features, such as forms and hyperlinks (Perry). HTML is a good tool for publishing small file size documents over the Internet. However, HTML in its traditional form is not powerful enough to create the interactive and multitude-rich documents that today’s commercial web sites demand. HTML’s limitation is the control over page layout. Web authors do not have the ability to lay out pages with the pixel-level accuracy available to the traditional desktop publishing author. In addition, a standard HTML document cannot specify that text and images are located at exact coordinates, on top of each other, or even that the text be displayed in a particular point size (Heinle). Most computer programming languages have more functionality than HTML. The programming language is called JavaScript and it has powerful range of command. In order to combine these two programming languages together to be more powerful, Dynamic HTML emerged

Enhanced User Experience DHTML makes the Web experience faster and more interactive for end users. Live updates can be activated by user and browser-driven events. For example, text and images can be hidden in a document until a user moves the mouse over an element or clicks a button. A browser-driven event can be triggered by internal actions, such as when the browser finishes downloading the Web page. DHTML uses Cascading Style Sheets which provides absolute positioning of every object on a page. Web designers can have precise 3-D control over x, y, and z coordinates. That means text and graphics can overlay each other, creating more visual effects. Data binding is a technique that ties elements in a Web page to a data source. It allows the creation of a Web page that displays up-to-the-minute data extracted from a database. When the page is loaded, the current information from the data source can be read and inserted in a table. The data can be Training & Development Division

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dynamically updated or sorted through a script without redrawing the page or having to go back to the server. Data binding is supported by IE4 but not by NN4. In a client-server environment, DHTML lets the client/browser make changes after a web page has been downloaded, without the burden of relying on server-side programs or complicated sets of HTML pages to achieve special effects. In other words, the client does not need to reload the document or load a new document, or require a remote server to generate new content. That means a user does not have to wait for text and data to complete time and bandwidth consuming round-trips to and from a server before seeing results.

Components of DHTML DHTML requires four independent components to work: HTML, Cascading Style Sheets, Scripting and the Document Object Model. The section provides a brief description of each component. HTML: HTML defines the structure of a Web page, using such basic elements as headings, forms, tables, paragraphs and links. On December 18, 1997, HTML 4.0 attained "recommended" status at the W3C. Changes and enhancements introduced in HTML 4.0 made DHTML possible. Cascading Style Sheets (CSS): Similar to a template in a word-processing document, a style sheet controls the formatting of HTML elements. Like in traditional desktop publishing, one can use style sheet to specify page margins, point sizes and leading. Cascading Style Sheets is a method to determine precedence and to resolve conflicts when multiple styles are used. Scripting: Scripting provides the mechanisms to interpret user actions and produce client-side changes to a page. For example, scripts can interpret mouse actions (such as the mouse passing over a specified area of a page through the event model) and respond to the action by using a set of predefined instructions (such as highlighting the text activated by the mouse action). Although DHTML can communicate with several scripting languages, JavaScript is the de facto standard for creating crossbrowser DHTML pages. Document Object Model (DOM): The DOM outlines Web page content in a way that makes it possible for HTML elements, style sheets and scripting languages to interact with each other. The W3C defines the DOM as "a platform- and language-neutral interface that will allow programs and scripts to dynamically access and update the content, structure, and style of documents. The document can be further processed and the results of that processing can be incorporated back into the presented stage."

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Review Questions 1. DHTML a. b. c. d.

is extension of _______ language. HTML SGML JScript XML

2. One of the main technologies in DHTML is ______. a. Exception handling b. Scripting Languages c. Text Designing d. Animation 3. State True or False. Using DHTML, we can do client side form Validation. a. True b. False

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Summary Dynamic HTML is an extension of HTML. It contains a number of new tags that lets you define a user interface in terms of HTML elements and lets users interact with that interface. DHTML consists of a number of related technologies like HTML who defines the structure of the information being conveyed to the user, Cascading Style Sheets (CSS) determines the appearance of that information as it is being rendered, and the Document Object Model (DOM). Scripting languages such as VBScript and JavaScript interact with the HTML elements in the document. Netscape and Microsoft have pledged future support for a standard that is currently being decided by the World Wide Web Consortium (W3C).

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HTML, DHTML & JavaScript Chapter 14: Introduction to CSS

Objectives • • • • •

Understanding basics of CSS To know the benefits of using CSS To explore syntax of CSS Understanding various types of CSS Learning various selectors in CSS like font, background

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Cascading Style Sheets (CSS) is a fantastic tool to add layout to your websites. It can save you a lot of time and it enables you to design websites in a completely new way. CSS is a must for anyone working with web design. This tutorial will get you started with CSS in just a few hours. It is easy to understand and it will teach you all the sophisticated techniques. Learning CSS is fun. As you go along through the tutorial, remember to take enough time to properly experiment with what you learn in each lesson. Using CSS requires basic experience with HTML.

Which software do you need? Please avoid using software such as FrontPage, DreamWeaver or Word with this. Advanced software will not help you learn CSS. Instead, it will limit you and slow down your learning curve significantly. All you need is a free and simple text editor. For example, Microsoft Windows comes with a program called Notepad. It is usually located in Accessories in the start menu under Programs. Alternatively, you can use a similar text editor e.g. Pico for Linux or Simple Text for Macintosh. A simple text editor is ideal for learning HTML and CSS because it doesn't affect or change the codes you type. That way, your successes and errors can only be attributed to yourself - not the software. You can use any browser for this session. We encourage you to always keep your browser updated and use the latest version. A browser and a simple text editor is all you need.

What is CSS? May be you already heard about CSS without really knowing what it is. In this lesson you will learn more about what CSS is and what it can do for you. CSS is an acronym for Cascading Style Sheets.

What can I do with CSS? CSS is a style language that defines layout of HTML documents. For example, CSS covers fonts, colors, margins, lines, height, width, background images, advanced positions and many other things. Just wait and see! HTML can be (mis-)used to add layout to websites. But CSS offers more options and is more accurate and sophisticated. CSS is supported by all browsers today. After only a few lessons of this tutorial, you will be able to make your own style sheets using CSS to give your website a new great look.

What is the difference between CSS and HTML? HTML is used to structure content. CSS is used for formatting structured content. Okay, it sounds a bit technical and confusing. But please continue reading. It will all make sense to you soon. Back in the good old days a guy called Tim Berners Lee invented the World Wide Web, the language HTML was only used to add structure to text. An author could mark his text by stating "this is a headline" or "this is a paragraph" using HTML tags such as and . Training & Development Division

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As the Web gained popularity, designers started looking for possibilities to add layout to online documents. To meet this demand, the browser producers (at that time Netscape and Microsoft) invented new HTML tags such as for example which differed from the original HTML tags by defining layout - and not structure. This also led to a situation where original structure tags such as were increasingly being misused to layout pages instead of adding structure to text. Many new layout tags such as were only supported by one type of browser. "You need browser X to view this page" became a common disclaimer on web sites. CSS was invented to remedy this situation by providing web designers with sophisticated layout opportunities supported by all browsers. At the same time, separation of the presentation style of documents from the content of documents makes site maintenance a lot easier.

Which benefits will CSS give you? CSS was a revolution in the world of web design. The concrete benefits of CSS include: •

Control layout of many documents from one single style sheet

•

More precise control of layout

•

Apply different layout to different media-types (screen, print, etc.)

•

Numerous advanced and sophisticated techniques

How does CSS work? Here you will learn how to make your first style sheet. You will get to know about the basic CSS model and which codes are necessary to use CSS in an HTML document. Many of the properties used in Cascading Style Sheets (CSS) are similar to those of HTML. Thus, if you are used to use HTML for layout, you will most likely recognize many of the codes. Let us look at a concrete example. The basic CSS syntax Let's say we want a nice red color as the background of a webpage: Using HTML we could have done it like this: With CSS the same result can be achieved like this: body {background-color: #FF0000;} As you will note, the codes are more or less identical for HTML and CSS. The above example also shows you the fundamental CSS model:

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But where do you put the CSS code? This is exactly what we will go over now.

Applying CSS to an HTML document There are three ways you can apply CSS to an HTML document. These methods are all outlined below. We recommend that you focus on the third method i.e. external. Method 1: In-line (the attribute style) One way to apply CSS to HTML is by using the HTML attribute style. Building on the above example with the red background color, it can be applied like this: Example This is a red page Method 2: Internal (the tag style) Another way is to include the CSS codes using the HTML tag . For example like this: Example body {background-color: #FF0000;} This is a red page Method 3: External (link to a style sheet) The recommended method is to link to a so-called external style sheet. Throughout this tutorial we will use this method in all our examples. An external style sheet is simply a text file with the extension .css. Like any other file, you can place the style sheet on your web server or hard disk.

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For example, let's say that your style sheet is named style.css and is located in a folder named style. The situation can be illustrated like this:

The trick is to create a link from the HTML document (default.htm) to the style sheet (style.css). Such link can be created with one line of HTML code: Notice how the path to our style sheet is indicated using the attribute href. The line of code must be inserted in the header section of the HTML code i.e. between the and tags. Like this: My document ...

This link tells the browser that it should use the layout from the CSS file when displaying the HTML file. The really smart thing is that several HTML documents can be linked to the same style sheet. In other words, one CSS file can be used to control the layout of many HTML documents.

This technique can save you a lot of work. If you, for example, would like to change the background color of a website with 100 pages, a style sheet can save you from having to manually change all 100 HTML documents. Using CSS, the change can be made in a few seconds just by changing one code in the central style sheet.

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Try it yourself Open Notepad (or whatever text editor you use) and create two files - an HTML file and a CSS file with the following contents: default.htm My document My first stylesheet style.css body { background-color: #FF0000; } Now place the two files in the same folder. Remember to save the files with the right extensions (respectively ".htm" and ".css") Open default.htm with your browser and see how the page has a red background. Congratulations! You have made your first style sheet!

Colors and backgrounds In this lesson you will learn how to apply colors and background colors to your websites. We will also look at advanced methods to position and control background images. The following CSS properties will be explained: •

color

•

background-color

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background-image

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background-repeat

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background-attachment

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background-position

•

background

Foreground color: the 'color' property The color property describes the foreground color of an element. For example, imagine that we want all headlines in a document to be dark red. The headlines are all marked with the HTML element . The code below sets the color of elements to red. h1 { color: #ff0000; } Training & Development Division

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Colors can be entered as hexadecimal values as in the example above (#ff0000), or you can use the names of the colors ("red") or rgb-values (rgb(255,0,0)). The 'background-color' property The background-color property describes the background color of elements. The element contains all the content of an HTML document. Thus, to change the background color of an entire page, the background-color property should be applied to the element. You can also apply background colors to other elements including headlines and text. In the example below, different background colors are applied to and elements. body { background-color: #FFCC66; } h1 { color: #990000; background-color: #FC9804; } Notice that we applied two properties to by dividing them by a semicolon. Background images [background-image] The CSS property background-image is used to insert a background image. As an example of a background image, we use the butterfly below. You can download the image so you can use it on your own computer (right click the image and choose "save image as"), or you can use another image as you see fit.

To insert the image of the butterfly as a background image for a web page, simply apply the background-image property to and specify the location of the image.

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body { background-color: #FFCC66; background-image: url("butterfly.gif"); } h1 { color: #990000; background-color: #FC9804; }

Note: Notice how we specified the location of the image as url("butterfly.gif"). This means that the image is located in the same folder as the style sheet. You can also refer to images in other folders using url("../images/butterfly.gif") or even on the Internet indicating the full address of the file: url("http://www.html.net/butterfly.gif").

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Repeat background image [background-repeat] In the example above, did you notice that by default the butterfly was repeated both horizontally and vertically to cover the entire screen? The property background-repeat controls this behavior. The table below outlines the four different values for background-repeat. Value

Description

background-repeat: repeat-x

The image is repeated horizontally

background-repeat: repeat-y

The image is repeated vertically

background-repeat: repeat

The image is repeated both horizontally and vertically

background-repeat: no-repeat The image is not repeated For example, to avoid repetition of a background image the code should look like this: body { background-color: #FFCC66; background-image: url("butterfly.gif"); background-repeat: no-repeat; } h1 { color: #990000; background-color: #FC9804; }

Lock background image [background-attachment] The property background-attachment specifies whether a background picture is fixed or scrolls along with the containing element. A fixed background image will not move with the text when a reader is scrolling the page, whereas an unlocked background image will scroll along with the text of the web page. The table below outlines the two different values for background-attachment. Click on the examples to see the difference between scroll and fixed. Value

Description

Background-attachment: scroll The image scrolls with the page - unlocked Background-attachment: fixed The image is locked For example, the code below will fix the background image. body { background-color: #FFCC66; background-image: url("butterfly.gif"); background-repeat: no-repeat; background-attachment: fixed; } h1 { color: #990000; background-color: #FC9804; }

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Place background image [background-position] By default, a background image will be positioned in the top left corner of the screen. The property background-position allows you to change this default and position the background image anywhere you like on the screen. There are numerous ways to set the values of background-position. However, all of them are formatted as a set of coordinates. For example, the value '100px 200px' positions the background image 100px from the left side and 200px from the top of the browser window. The coordinates can be indicated as percentages of the browser window, fixed units (pixels, centimetres, etc.) or you can use the words top, bottom, center, left and right. The model below illustrates the system:

The table below gives some examples. Value

Description

background-position: 2cm 2cm The image is positioned 2 cm from the left and 2 cm down the page background-position: 50% 25% The image is centrally positioned and one fourth down the page background-position: top right The image is positioned in the top-right corner of the page The code example below positions the background image in the bottom right corner: body { background-color: #FFCC66; background-image: url("butterfly.gif"); background-repeat: no-repeat; background-attachment: fixed; background-position: right bottom; } Training & Development Division

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h1 { color: #990000; background-color: #FC9804; }

Compiling [background] The property background is a short hand for all the background properties listed in this lesson. With background you can compress several properties and thereby write your style sheet in a shorter way which makes it easier to read. For example, look at these five lines: background-color: #FFCC66; background-image: url("butterfly.gif"); background-repeat: no-repeat; background-attachment: fixed; background-position: right bottom; Using background the same result can be achieved in just one line of code: background: #FFCC66 url("butterfly.gif") no-repeat fixed right bottom; The list of order is as follows: [background-color] | [background-image] | [background-repeat] | [background-attachment] | [background-position] If a property is left out, it will automatically be set to its default value. For example, if backgroundattachment and background-position are taken out of the example: background: #FFCC66 url("butterfly.gif") no-repeat; These two properties that are not specified would merely be set to their default values which as you know are scroll and top left.

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Fonts In this lesson you will learn about fonts and how they are applied using CSS. We will also look at how to work around the issue that specific fonts chosen for a website can only be seen if the font is installed on the PC used to access the website. The following CSS properties will be described: •

font-family

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font-style

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font-variant

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font-weight

•

font-size

•

font

Font family [font-family] The property font-family is used to set a prioritized list of fonts to be used to display a given element or web page. If the first font on the list is not installed on the computer used to access the site, the next font on the list will be tried until a suitable font is found. There are two types of names used to categorize fonts: family-names and generic families. The two terms are explained below. Family-name Examples of a family-name (often known as "font") can e.g. be "Arial", "Times New Roman" or "Tahoma". Generic family Generic families can best be described as groups of family-names with uniformed appearances. An example is sans-serif, which is a collection of fonts without "feet". The difference can also be illustrated like this:

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When you list fonts for your web site, you naturally start with the most preferred font followed by some alternative fonts. It is recommended to complete the list with a generic font family. That way at least the page will be shown using a font of the same family if none of the specified fonts are available. An example of a prioritized list of fonts could look like this: h1 {font-family: arial, verdana, sans-serif;} h2 {font-family: "Times New Roman", serif;} Headlines marked with will be displayed using the font "Arial". If this font is not installed on the user's computer, "Verdana" will be used instead. If both these fonts are unavailable, a font from the sans-serif family will be used to show the headlines. Notice how the font name "Times New Roman" contains spaces and therefore is listed using quotation marks. Font style [font-style] The property font-style defines the chosen font either in normal, italic or oblique. In the example below, all headlines marked with will be shown in italics. h1 {font-family: arial, verdana, sans-serif;} h2 {font-family: "Times New Roman", serif; font-style: italic;}

Font variant [font-variant] The property font-variant is used to choose between normal or small-caps variants of a font. A smallcaps font is a font that uses smaller sized capitalized letters (upper case) instead of lower case letters. Confused? Take a look at these examples:

If font-variant is set to small-caps and no small-caps font is available the browser will most likely show the text in uppercase instead. h1 {font-variant: small-caps;} h2 {font-variant: normal;}

Font weight [font-weight] The property font-weight describes how bold or "heavy" a font should be presented. A font can either be normal or bold. Some browsers even support the use of numbers between 100-900 (in hundreds) to describe the weight of a font. p {font-family: arial, verdana, sans-serif;} td {font-family: arial, verdana, sans-serif; font-weight: bold;}

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Font size [font-size] The size of a font is set by the property font-size. There are many different units (e.g. pixels and percentages) to choose from to describe font sizes. In this tutorial we will focus on the most common and appropriate units. Examples include: h1 {font-size: 30px;} h2 {font-size: 12pt;} h3 {font-size: 120%;} p {font-size: 1em;} There is one key difference between the four units above. The units 'px' and 'pt' make the font size absolute, while '%' and 'em' allow the user to adjust the font size as he/she see fit. Many users are disabled, elderly or simply suffer from poor vision or a monitor of bad quality. To make your website accessible for everybody, you should use adjustable units such as '%' or 'em'. Below you can see an illustration of how to adjust the text size in Mozilla Firefox and Internet Explorer. Try it yourself - neat feature, don't you think?

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Compiling [font] Using the font short hand property it is possible to cover all the different font properties in one single property. For example, imagine these four lines of code used to describe font-properties for : p{ font-style: italic; font-weight: bold; font-size: 30px; font-family: arial, sans-serif; } Using the short hand property, the code can be simplified: p{ font: italic bold 30px arial, sans-serif; } The order of values for font is: font-style | font-variant | font-weight | font-size | font-family

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Text Formatting and adding style to text is a key issue for any web designer. In this lesson you will be introduced to the amazing opportunities CSS gives you to add layout to text. The following properties will be described: •

text-indent

•

text-align

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text-decoration

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letter-spacing

•

text-transform

Text indention [text-indent] The property text-indent allows you to add an elegant touch to text paragraphs by applying an indent to the first line of the paragraph. In the example below a 30px is applied to all text paragraphs marked with : p{ text-indent: 30px; } Text alignment [text-align] The CSS property text-align corresponds to the attribute align used in old versions of HTML. Text can either be aligned to the left, to the right or centered. In addition to this, the value justify will stretch each line so that both the right and left margins are straight. You know this layout from for example newspapers and magazines. In the example below the text in table headings is aligned to the right while the table data are centered. In addition, normal text paragraphs are justified: th { text-align: right; } td { text-align: center; } p{ text-align: justify; }

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Text decoration [text-decoration] The property text-decoration makes it possible to add different "decorations" or "effects" to text. For example, you can underline the text; have a line through or above the text, etc. In the following example, are underlined headlines, are headlines with a line above the text and are headlines with a line though the text. h1 { text-decoration: underline; } h2 { text-decoration: overline; } h3 { text-decoration: line-through; }

Letter space [letter-spacing] The spacing between text characters can be specified using the property letter-spacing. The value of the property is simply the desired width. For example, if you want a spacing of 3px between the letters in a text paragraph and 6px between letters in headlines the code below could be used. h1 { letter-spacing: 6px; } p{ letter-spacing: 3px; } Text transformation [text-transform] The text-transform property controls the capitalization of a text. You can choose to capitalize, use uppercase or lowercase regardless of how the original text is looks in the HTML code. An example could be the word "headline" which can be presented to the user as "HEADLINE" or "Headline". There are four possible values for text-transform: capitalize Capitalizes the first letter of each word. For example: "john doe" will be "John Doe". uppercase Converts all letters to uppercase. For example: "john doe" will be "JOHN DOE". lowercase Converts all letters to lowercase. For example: "JOHN DOE" will be "john doe". none No transformations - the text is presented as it appears in the HTML code. As an example, we will use a list of names. The names are all marked with (list-item). Let's say that we want names to be capitalized and headlines to be presented in uppercase letters. Try to take a look at the HTML code for this example and you will see that the text actually is in lowercase. h1 { text-transform: uppercase; Training & Development Division

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} li { text-transform: capitalize; }

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Links You can apply what you already learnt in the previous lessons to links (i.e. change colors, fonts, underline, etc). The new thing is that CSS allows you to define these properties differently depending on whether the link is unvisited, visited, active, or whether the cursor is on the link. This makes it possible to add fancy and useful effects to your website. To control these effects you use so-called pseudo-classes. What is a pseudo-class? A pseudo-class allows you to take into account different conditions or events when defining a property for an HTML tag. Let's look at an example. As you know, links are specified in HTML with tags. We can therefore use a as a selector in CSS: a{ color: blue; } A link can have different states. For example, it can be visited or not visited. You can use pseudoclasses to assign different styles to visited and unvisited links. a:link { color: blue; } a:visited { color: red; } Use a:link and a:visited for unvisited and visited links respectively. Links that are active have the pseudo-class a:active and a:hover is when the cursor is on the link. We will now go through each of the four pseudo-classes with examples and further explanation. Pseudo-class: link The pseudo-class: link is used for links leading to pages that the user has not visited. In the code example below, unvisited links will be light blue. a: link { color: #6699CC; }

Pseudo-class: visited The pseudo-class :visited is used for links leading to pages that the user has visited. For example, the code below would make all visited links dark purple: a:visited { color: #660099; }

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Pseudo-class: active The pseudo-class: active is used for links that are active. This example gives active links a yellow background color: a: active { background-color: #FFFF00; }

Pseudo-class: hover The pseudo-class: hover is used when the mouse pointer hovers over a link. This can be used to create interesting effects. For example, if we want our links to be orange and be italicized when the cursor is pointed at them, our CSS should look like this: a: hover { color: orange; font-style: italic; } Example 1: Effect when the cursor is over a link It is particular popular to create different effects when the cursor is over a link. We will therefore look at a few extra examples related to the pseudo-class: hover. Example 1a: Spacing between letters As you will remember, the spacing between letters can be adjusted using the property letter-spacing. This can be applied to links for a special effect: a:hover { letter-spacing: 10px; font-weight:bold; color:red; }

Example 1b: UPPERCASE and lowercase In last session we looked at the property text-transform, which can switch between upper- and lowercase letters. This can also be used to create an effect for links: a:hover { text-transform: uppercase; font-weight:bold; color:blue; background-color:yellow; }

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The two examples gives you an idea about the almost endless possibilities for combining different properties. You can create your own effects - give it a try! Example 2: Remove underline of links A frequently asked question is how to remove the underlining of links? You should consider carefully whether it is necessary to remove the underlining as it might decrease usability of your website significantly. People are used to blue underlined links on web pages and know that they can click on them. Even my mum knows that! If you change the underlining and color of links there is a good chance that users will get confused and therefore not get the full benefit of the content on your website. That said, it is very simple to remove the underlining of links. As you will recall from one of the previous sessions, the property text-decoration can be used to determine whether text is underlined or not. To remove underlining, simply set the value of text-decoration to none. a{ text-decoration:none; } Alternatively, you can set text-decoration along with other properties for all four pseudo-classes. a:link { color: blue; text-decoration:none; } a:visited { color: purple; text-decoration:none; } a:active { background-color: yellow; text-decoration:none; } a:hover { color:red; text-decoration:none; }

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Identification and grouping of elements (class and id) Sometimes you want to apply a special style to a particular element or a particular group of elements. In this lesson, we will take a closer look at how you can use class and id to specify properties for selected elements. How can you color one particular headline differently than the other headlines on your website? How can you group your links into different categories and give each category a special style? These are just examples of questions we will answer in this lesson.

Grouping elements with class Let's say that we have two lists of links of different grapes used for white wine and red wine. The HTML code could look like this: Grapes for white wine: Riesling Chardonnay Pinot Blanc Grapes for red wine: Cabernet Sauvignon Merlot Pinot Noir Then we want the white wine links to be yellow, the red wine links to be red and the rest of the existing links on the webpage to stay blue. To achieve this, we divide the links into two categories. This is done by assigning a class to each link using the attribute class. Let us try to specify some classes in the example above: Grapes for white wine: Riesling Chardonnay Pinot Blanc Grapes for red wine: Cabernet Sauvignon Merlot Pinot Noir We can hereafter define special properties for links belonging to whitewine and redwine, respectively.

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a{ color: blue; } a.whitewine { color: #FFBB00; } a.redwine { color: #800000; } As shown in the example you can define the properties for elements which belong to a certain class by using .classname in the style sheet of the document.

Identification of element using id In addition to grouping elements, you might need to identify one unique element. This is done by using the attribute id. What is special about the attribute id is that there can not be two elements in the same document with the same id. Each id has to be unique. In other cases, you should use the class attribute instead. Now, let us take a look at an example of a possible usage of id: Chapter ... Chapter ... Chapter ... Chapter ... Chapter ... Chapter ...

1 1.1 1.2 2 2.1 2.1.2

The above could be headings of any document split into chapters or paragraphs. It would be natural to assign an id to each chapter as follows: Chapter 2.1.2

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Let us say that the headline for chapter 1.2 must be in red. This can be done accordingly with CSS: #c1-2 { color: red; } As shown in the example above you can define the properties in a specific element by using #id in the stylesheet of the document.

Grouping of elements (span and div) The elements and are used to group and structure a document and will often be used together with the attributes class and id. In this lesson, we will take a closer look at the use of and as exactly these two HTML elements are of central importance with regards to CSS. •

Grouping with

•

Grouping with

Grouping with The element is what you could call a neutral element which does not add anything to the document itself. But with CSS, can be used to add visual features to specific parts of text in your documents. An example of this could be this Benjamin Franklin quotation: Early to bed and early to rise makes a man healthy, wealthy and wise. Lets us say we want what Mr. Franklin sees as the benefits of not sleeping your day away emphasized in red. For that purpose, we can mark the benefits with . Each span is then added a class, which we can define in our style sheet: Early to bed and early to rise makes a man healthy, wealthy and wise. The CSS belonging to it: span.benefit { color:red; }

Of course you may also use id to add style to the -elements. Just as long as you remember, that you'll have to apply a unique id to each of the three -elements, as you learnt in the previous lesson.

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Grouping with Whereas is used within a block-level element as seen in the previous example, is used to group one or more block-level elements. Aside from this difference, the grouping with works in more or less the same way. Let us take a look at an example with two lists of U.S. presidents divided into their political affiliations: Franklin D. Roosevelt Harry S. Truman John F. Kennedy Lyndon B. Johnson Jimmy Carter Bill Clinton Dwight D. Eisenhower Richard Nixon Gerald Ford Ronald Reagan George Bush George W. Bush And in our style sheet, we can utilize the grouping in the exact same way as above: #democrats { background:blue; } #republicans { background:red; }

In the examples above, we have only used and on very simple things such as text and background colors. Both elements have the potential to do much more advanced things. However this will not be introduced in this lesson. We will look into these later in this tutorial.

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The box model The box model in CSS describes the boxes which are being generated for HTML-elements. The box model also contains detailed options regarding adjusting margin, border, padding and content for each element. The diagram below shows how the box model is constructed: The box model in CSS

The illustration above might seem pretty theoretical to look at, so let's try to use the model in an actual case with a headline and some text. The HTML for our example is (from the Universal Declaration of Human Rights): Article 1: All human beings are born free and equal in dignity and rights. They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood By adding some color and font-information the example could be presented as follows:

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The example contains two elements: and . The box model for the two elements can be illustrated as follows:

Even though it may look a bit complicated, the illustration shows how each HTML-element is surrounded by boxes. Boxes which we can adjust using CSS.

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Margin and padding In the previous lesson you were introduced to the box model. In this lesson, we will look at how you can change the presentation of elements by setting the margin and padding properties. •

Set the margin in an element

•

Set the padding in an element

Set the margin in an element An element has four sides: right, left, top and bottom. The margin is the distance from each side to the neighboring element (or the borders of the document). As the first example, we will look at how you define margins for the document itself i.e. for the element . The illustration below shows how we want the margins in our pages to be.

The CSS code for this would look as follow: body { margin-top: 100px; margin-right: 40px; margin-bottom: 10px; margin-left: 70px; } Or you could choose a more elegant compilation: body { margin: 100px 40px 10px 70px; }

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You can set the margins in the same way on almost every element. For example, we can choose to define margins for all of our text paragraphs marked with : body { margin: 100px 40px 10px 70px; } p{ margin: 5px 50px 5px 50px; } Set padding in an element Padding can also be understood as "filling". This makes sense as padding does not affect the distance of the element to other elements but only defines the inner distance between the border and the content of the element. The usage of padding can be illustrated by looking at a simple example where all headlines have background colors: h1 { background: yellow; } h2 { background: orange; } By defining padding for the headlines, you change how much filling there will be around the text in each headline: h1 { background: yellow; padding: 20px 20px 20px 80px; } h2 { background: orange; padding-left:120px; }

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Borders Borders can be used for many things, for example as a decorative element or to underline a separation of two things. CSS gives you endless options when using borders in your pages. •

border-width

•

border-color

•

border-style

•

border

The width of borders [border-width] The width of borders is defined by the property border-width, which can obtain the values thin, medium, and thick, or a numeric value, indicated in pixels. The figure below illustrates the system:

The color of borders [border-color]

The property border-color defines which color the border has. The values are the normal color-values for example "#123456", "rgb(123,123,123)" or "yellow". Types of borders [border-style] There are different types of borders to choose from. Below are shown 8 different types of borders as Internet Explorer 5.5 interprets them. All examples are shown with the color "gold" and the thickness "thick" but can naturally be shown in other colors and thicknesses. The values none or hidden can be used if you do not want any border.

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Examples of defining borders The three properties described above can be put together by each element and thereby produce different borders. To illustrate this, we will take a look at a document where we define different borders for , , and . The result may not be that pretty but it illustrates some of the many possibilities: h1 { border-width: thick; border-style: dotted; border-color: gold; } h2 { border-width: 20px; border-style: outset; border-color: red; } p{ border-width: 1px; border-style: dashed; border-color: blue; } ul { border-width: thin; border-style: solid; border-color: orange; }

It is also possible to state special properties for top-, bottom-, right- or left borders. The following example shows you how: h1 { border-top-width: thick; border-top-style: solid; border-top-color: red; border-bottom-width: thick; border-bottom-style: solid; border-bottom-color: blue; border-right-width: thick; border-right-style: solid; border-right-color: green; border-left-width: thick; border-left-style: solid; border-left-color: orange; }

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Compilation [border] As it is also the case for many other properties, you can compile many properties into one using border. Let us take a look at an example: p{ border-width: 1px; border-style: solid; border-color: blue; } Can be compiled into: p{ border: 1px solid blue; }

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Height and width Up until now, we have not cared much about the dimensions of the elements we have worked with. In this lesson, we will take a look at how you easily can define the height and width of an element. •

width

•

height

Setting the width [width] With the width-property, you can define a certain width of an element. The simple example below provides us with a box wherein text can be typed: div.box { width: 200px; border: 1px solid black; background: orange; }

Setting the height [height] In the example above notice how the height of the box is set by the content of the box. You can affect the height of an element with the property height. As an example let us try to make the box in the example 500px high: div.box { height: 500px; width: 200px; border: 1px solid black; background: orange; }

Floating elements (floats) An element can be floated to the right or to left by using the property float. That is to say that the box with its contents either floats to the right or to the left in a document (or the containing box). The following figure illustrates the principle:

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If we for example would like to have a text wrapping around a picture, the result would be like this:

How is it done? The HTML code for the example above, look as follows: causas naturales et antecedentes, idciro etiam nostrarum voluntatum... To get the picture floating to the left and the text to surround it, you only have to define the width of the box which surrounds the picture and thereafter set the property float to left: #picture { float:left; width: 100px; } Another example: columns Floats can also be used for columns in a document. To create the columns, you simply have to structure the desired columns in the HTML-code with as follows: Haec disserens qua de re agatur et in quo causa consistat non videt... causas naturales et antecedentes, idciro etiam nostrarum voluntatum... nam nihil esset in nostra potestate si res ita se haberet... Training & Development Division

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Now the desired width of the columns is set to e.g. 33%, and then you simply float each column to the left by defining the property float: #column1 { float:left; width: 33%; } #column2 { float:left; width: 33%; } #column3 { float:left; width: 33%; } float can be set as either left, right or none. The property clear The clear property is used to control how the subsequent elements of floated elements in a document shall behave. By default, the subsequent elements are moved up to fill the available space which will be freed when a box is floated to a side. Look at the example above wherein the text is automatically moved up beside the picture of Bill Gates. The property clear can assume the values left, right, both or none. The principle is, if clear, for example, is set to both for a box, the top margin border of this box will always be under the lower margin border for possible floating boxes coming from above. Bill Gates causas naturales et antecedentes, idciro etiam nostrarum voluntatum... To avoid the text from floating up next to the picture, we can add the following to our CSS: #picture { float:left; width: 100px; } .floatstop { clear:both; }

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Positioning of elements With CSS positioning, you can place an element exactly where you want it on your page. Together with floats, positioning gives you many possibilities to create an advanced and precise layout. The following will be discussed in this lesson: •

The principle behind CSS positioning

•

Absolute positioning

•

Relative positioning

The principle behind CSS positioning Imagine a browser window as a system of coordinates:

The principle behind CSS positioning is that you can position any box anywhere in the system of coordinates. Let's say we want to position a headline. By using the box model the headline will appear as follows:

If we want this headline positioned 100px from the top of the document and 200px from the left of the document, we could type the following in our CSS: h1 { position:absolute; top: 100px; left: 200px; }

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The result will be as follows:

As you can see, positioning with CSS is a very precise technique to place elements. It is much easier than trying to use tables, transparent images or anything else. Absolute positioning An element which is positioned absolute does not obtain any space in the document. This means that it does not leave an empty space after being positioned. To position an element absolutely, the position property is set as absolute. You can subsequently use the properties left, right, top, and bottom to place the box. As an example of absolute positioning, we choose to place 4 boxes in each corner of the document: #box1 { position:absolute; top: 50px; left: 50px; } #box2 { position:absolute; top: 50px; right: 50px; } #box3 { position:absolute; bottom: 50px; right: 50px; }

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#box4 { position:absolute; bottom: 50px; left: 50px; }

Relative positioning To position an element relatively, the property position is set as relative. The difference between absolute and relative positioning is how the position is being calculated. The position for an element which is relatively positioned is calculated from the original position in the document. That means that you move the element to the right, to the left, up or down. This way, the element still obtains a space in the document after it is positioned. As an example of relative positioning, we can try to position three pictures relatively to their original position on the page. Notice how the pictures leave empty spaces at their original positions in the document: #dog1 { position:relative; left: 350px; bottom: 150px; } #dog2 { position:relative; left: 150px; bottom: 500px; } #dog3 { position:relative; left: 50px; bottom: 700px; }

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Layer on layer with z-index (Layers) CSS operates in three dimensions - height, width and depth. We have seen the first two dimensions in previous lessons. In this lesson, we will learn how to let different elements become layers. In short, this means the order of which the elements overlap one another. For that purpose, you can assign each element a number (z-index). The system is that an element with a higher number overlaps an element with a lower number. Let us say we are playing poker and have a royal flush. Our hand can be presented in a way where each card has got a z-index:

In this case, the numbers follow on another (1-5) but the same result can be obtained by using 5 different numbers. The important thing is the chronological sequence of the numbers (the order). The code in the card example could look like this: #ten_of_diamonds { position: absolute; left: 100px; bottom: 100px; z-index: 1; } #jack_of_diamonds { position: absolute; left: 115px; bottom: 115px; z-index: 2; } #queen_of_diamonds { position: absolute; left: 130px; bottom: 130px; z-index: 3; } #king_of_diamonds { position: absolute; left: 145px; Training & Development Division

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bottom: 145px; z-index: 4; } #ace_of_diamonds { position: absolute; left: 160px; bottom: 160px; z-index: 5; } The method is relatively simple but the possibilities are several. You can place images on text or text above text etc.

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Review Questions 1. Which would you NOT be able to do with CSS? a. Add text b. Position the content c. Define the look of your pages in one place 2. In CSS, a. b. c. d.

what is a definition of fonts, colours, etc. called? ID tag Style Font-family Selector map

3. When changing a style you must edit ______? a. The style definition only b. The settings on your browser c. All tags that refer to the style 4. is what kind of tag? a. Font tag b. Block tag c. Inline tag d. None from the options 5. CSS can be added to a page on how many levels? a. 3 - Tag, Head and External file b. 4 - Tag, Head, External file and Meta tag c. 2 - Head and External file d. There is no level limit

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Summary Cascading Style Sheets (CSS) is a fantastic tool to add layout to your website. We don’t require any special software to work with CSS. CSS is used for formatting structured contents. CSS will give you more precise control of layout. There are total three types of CSS, In-line Style Sheet, Internal Style Sheet and External Style Sheet. Various selectors like font, text, background can be used to control complete layout of the webpage. The major advantage of using CSS to specify fonts is that, at any given time, you can change font on an entire website in just a few minutes. CSS saves time and makes your life easier.

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HTML, DHTML & JavaScript Chapter 15: Introduction to JavaScript This section will provide you with the basics of what JavaScript is, and why you should use it. Objectives • • • •

To examine the Evolution of JavaScript and describe some of its key features To explain JavaScript fundamentals To understand difference between Interpreted programs versus Compiled programs To explain why to use JavaScript

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History of JavaScript Web pages made using only HTML are somewhat static with no interactivity and negligible user involvement. Interactive pages can be described as those that understand and process user behaviour (actions) like mouse movements, mouse button clicks, HTML button clicks etc. HTML tags are just instructions on document layout and structure; the display of the document in the window is dependent on the browser. Interactive pages cannot be built with only HTML, we need a programming language. Further, since the response time to user actions should be quick, the programming language has to be embedded in the browser itself. (Programs residing on servers can not bring about interactivity due to the time taken for sending the user input and receiving the response.) Keeping these things in mind, the people at Netscape came out with a client-side (read browser) language that was integrated with version 2 of Netscape Navigator. They called this language JavaScript. (Actually, JavaScript was initially christened LiveScript. Seeing the popularity gained by Sun Systems' Java, the bigwigs at Netscape changed its name... a clever marketing policy!) Microsoft's implementation of JavaScript is called JScript and was first introduced with version 3 of Internet Explorer. JavaScript is thus, a client-side scripting language. There is also a server-side version that is used in Active Server Pages, a technology promoted by Microsoft. This tutorial describes only client-side JavaScript. JavaScript enables browsers to take decisions and process information. This is the key to interactivity.

JavaScript versus JAVA JAVA is a strongly typed, compiled programming language developed by Sun Microsystems. JavaScript, developed originally by Netscape, is a lightweight, interpreted programming language initially called LiveScript. The two languages are not related in any way. All programming languages share a certain amount of similarity.

Interpreted programs versus Compiled programs Before we start discussing the differences between interpreted and compiled we have to define the term source code or as it is more commonly referred to, the code. The code is the plain text commands that the program is written in. All programming languages start out as source code; it is then either interpreted or compiled. The code that you will create in this course can be considered source code. Interpreted programming languages tend to be simpler to program but slower to execute in general. Each time a program is run it has to be interpreted (interrogated) line by line, based on the flow of execution (you will see later branches and loops affect the flow of execution). Compiled programming languages have a more complex syntax, and require more strict programming practices. With a compiled programming language you first write the source code, and then you feed it to a compiler (a special computer program) which produces an executable binary program. On the Windows platforms the output of the compiler usually ends in the ".exe" file extension. The program that comes out of the compilation process tends to be platform (operating system) specific. The key benefit for the programmer is that no other programmer can look at the source code once it is compiled. The other key factor is that the language used to write the source code becomes irrelevant once it has been compiled. JAVA is a compiled language that is platform independent, whereas JavaScript is an interpreted language. The browser provides the platform independence for JAVA through its JAVA Virtual Machine, and the interpreter for JavaScript. As a result, the browser you are writing your scripts for is important.

Why to Learn JavaScript JavaScript is the only scripting language currently supported by the popular web browsers. Netscape Navigator only supports JavaScript, whereas Microsoft Internet Explorer supports both JavaScript and VBScript. JavaScript can also be used on web servers for what's called server side scripting as well. The time you invest into learning the JavaScript language will provide you with what is now considered to be a core skill for web development. Training & Development Division

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What you can use JavaScript for Here are a few things you can do with JavaScript: •

Validate forms at the client-side saving both the precious server resources and time.

•

Create mouseover effects, change background colour of a document with a click of a button... interactivity!

•

Randomly display content without the involvement of server programs.

•

Move HTML elements around pages.

•

Change page contents dynamically.

•

Load content in new browser windows and frames.

•

Make online games.

Nature of JavaScript JavaScript is based on Object Oriented Programming concept. Its syntax is quite similar to C, C++ and Java. As it is based on Object Oriented Programming concepts, it is called as “Object Based”. However, it is much easier to learn and implement.

Other Client-side languages like JavaScript JScript: Invented by Microsoft, this language is similar to JavaScript. Supported by almost all the browsers. VBScript: Implemented only under Internet Explorer, this client-side language is similar to BASIC. It is commonly used in ASP technology. PerlScript: Similar to the Perl Language. Not well supported by all browsers.

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Review Questions 1. State True or False: JavaScript is an interpreted language. 2. JAVA is a ______________ programming language, and is platform ____________. 3. State True or False: JAVA and JavaScript were created by the same company. 4. Microsoft Internet Explorer supports the following scripting languages. a. JavaScript b. JAVA c. BASIC d. VBScript e. C++ f.

Perl

5. State True or False: JavaScript is supported by a large number of browsers.

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Summary JavaScript is not JAVA. JavaScript is Interpreted, and JAVA is Compiled programming language. Probably we would use JavaScript for various activities on webpage. JavaScript Language is not so powerful like any other programming language.

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HTML, DHTML & JavaScript Chapter 16: JavaScript Syntax In this chapter you will learn about the peculiarities of the JavaScript language. These are the details for writing a script that will help you avoid errors while you are creating your own scripts and learning the basics of the JavaScript programming language. Objectives • • • • • •

To place JavaScript in an HTML page To explain the Case-sensitivity of JavaScript To understand importance of Semicolons Understanding Whitespace, Brackets and Comments To declare Variable and Function Names To understand Reserved words in JavaScript

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Inserting Client Side JavaScript into an HTML Page JavaScript is added to an HTML page using the SCRIPT tag. The script tags should be placed inside the head tag of the document. If an older browser looks at a page containing script tags it will ignore them, as older browsers are written to ignore tags they can't interpret. JavaScript code should also be placed inside an HTML Comment tag set. E.g. When used with JavaScript the ending comment tag will also start with two slashes // which is the JavaScript code for comment. This tells the JavaScript interpreter to ignore that statement. This is a standard way for adding JavaScript to your HTML pages so that it works properly for browsers that are JavaScript enabled and those that do not support JavaScript. Web Page containing JavaScript (HTML document goes here) You may also put in a single line of code attached to an event. Events will be explained later. The general syntax for this structure is: stuff in between the opening and closing tag

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Creating your first JavaScript - JavaScript basics Learning a programming language is similar to picking up a sport. You arm yourself with a few statements and practice till you get the hang of them. Printing text with JavaScript Start a text editor (example, Notepad in Windows) and type the following: My First JavaScript Save this file with a .html or .htm extension and view it in a browser. The above code will produce output as:

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Explanation: document.write("This is JavaScript!"); is a JavaScript statement. Note the following points: •

The JavaScript statement is enclosed in the and tags.

•

The code informs the browser to write some text in the document. In this case, the text to be written is This is JavaScript!.

•

The text is enclosed in quotes and placed inside parenthesis. The quotes are NOT written along with the text; they help to signify the beginning and the end of the text.

Though, it is not necessary to end JavaScript statements with a semi-colon, it’s always a good habit.

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Syntax and Conventions Writing in any language follows rules and conventions. For example, the English language requires that each sentence must contain a subject and verb to be legitimate. You must also capitalize the first letter of a sentence, and end each sentence with punctuation such as a period or question mark. This is the syntax, or grammar of the English language. Each programming language has a similar set of rules commonly referred to as the syntax. JavaScript has several rules and conventions for its syntax: Case-sensitivity: JavaScript is a case-sensitive language, meaning that the language will treat these words differently: example, Example, EXAMPLE Semicolons: It is not compulsory that all statements should end with a semicolon. The semicolon separates one statement from another. i.e. var x = 0; var y = 10; White Space: JavaScript, like HTML, ignores spaces, tabs, and newlines that appear in statements. JavaScript does, however recognize spaces, tabs, and newlines that are part of a string. We will talk more about strings later in next sessions. var x=0; is the same as var x = 0; All of these examples will produce the same results. It is a good idea to put some spacing in your code to make it easier to read. It is not good programming practice to stretch statements over several lines. You do need a space between a programming command and the thing it is working on. For example, you need a space between var and the variable name. Strings and Quotes: A string is a sequence of zero or more characters enclosed within single or double quotes (‘single’, "double"). The double quotation mark can be found within strings that start, and end with (are delimited by) single quotes ('He said, "JavaScript is an interesting language." '). The single quotation mark can be used within a string delimited by double quotation marks. This syntax will be used quite often through out the JavaScripting codes. For example: In the example above you have line of HTML code that uses double quotes to delimit the tag's attributes. So to create a popup window that displays the string "You Clicked me" we need to enclose

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the string within single quotes. This is done so that the entire JavaScript statement is interpreted and the HTML syntax also remains valid. The Backslash (\) and Strings: The backslash character named as such because it leans backwards, and it should not be confused with the forwardslash character (/) that leans forwards. The backslash has a special purpose in JavaScript strings. It will be followed by another character that represents something in a string that cannot be typed on the keyboard. For example you want the word "You" to appear on one line and the word "Clicked" on a new line and "me" on a third line. The string would look like this: 'You\nClicked\nme' The ‘\n’ represents a carriage return and a line feed. These are the two operations that take place when you use the return on a typewriter. The results would look like this: You Clicked me These backslash and letter combinations are commonly referred to as escape sequences. Some of the common sequences are: \b

backspace

\f

form feed

\n

new line

\r

carriage return (no linefeed)

\t

tab

\'

single quote (apostrophe)

\"

double quote

The last two are important and can be used like this: 'You didn\'t get that done' or "You didn\'t get that done" The \ tells the interpreter that in this case it should print the single quote and not interpret it as a delimiter.

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Opening and Closing Brackets: All brackets you open must be closed! This includes ( ), [ ], and { }. i.e. winpop = window.open('ex1.htm','popup','scrollbars=yes'); if ( x[0] == 10 ) { x[0] = 0; x[1] = 0; } The curly brackets { } are used to contain multiple JavaScript statements. In the above example x[0]=0; and x[1]=0; are two different statements. The square brackets [ ] are part of a special data structure called arrays. Arrays will be covered later. The curved brackets ( ) are used to contain a function or a method’s arguments. Functions and methods will be described shortly. Multiple arguments are separated by commas. i.e. ('ex1.htm','popup','scrollbars=yes'). Comments: You can create a comment using the double forward slashes, like this: // this is a comment Or for multiple line comments you can open the comment with a forward slash and an asterisk "/*", and close it with an asterisk followed by a forward slash "*/" like this: /* Comments are often used by programmers to leave notes about their program logic so that when they return to update it, or someone else needs to edit it, they can understand what the programmer was doing at the time. */ Variable and Function Names In the next chapter you will be introduced to variables and functions. As the programmer you get to choose and assign the names. The names of the variables and functions must follow these simple rules. 1. The first character must be a letter of the alphabet (lowercase or uppercase), an underscore (_) or a dollar sign ($). The dollar sign is not recommended as it is not supported prior to JavaScript ver 1.1. 2. You CANNOT use a number as the first character of the name. 3. Names CANNOT contain spaces. 4. Names CANNOT match any of the reserved words. The following are examples of valid variable names:

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x add_two_num x13 _whatever $money_string We recommend that you use descriptive names for your variables and your functions and that you adopt a standard way of naming things. The two formats that are common are; using the underscore to replace spaces, or capitalizing the first letter of complete words after the first word in the name. For example: add_two_num addTwoNumbers JavaScript tends to use the latter for its naming conventions. Reserved Words There are a number of words that make up the components of the JavaScript language. These words cannot be used for variable or function names because the program interpreter would be unable to distinguish between a default JavaScript command and your variable or function name. abstract

delete

innerWidth

Packages

status

alert

do

instanceof

pageXOffset

statusbar

arguments

document

int

pageYOffset

stop

Array

double

interface

parent

String

blur

else

isFinite

parseFloat

super

boolean

enum

isNaN

parseInt

switch

Boolean

escape

java

personalbar

synchronized

break

eval

length

print

this

byte

export

location

private

throw

callee

extends

locationbar

prompt

throws

caller

final

long

protected

toolbar

captureEvents

finally

Math

prototype

top

case

find

menubar

public

toString

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catch

float

moveBy

RegExp

transient

char

focus

moveTo

releaseEvents

try

class

for

name

resizeBy

typeof

clearInterval

frames

NaN

resizeTo

unescape

clearTimeout

Function

native

return

unwatch

close

function

netscape

routeEvent

valueOf

closed

goto

new

scroll

var

confirm

history

null

scrollbars

void

const

home

Number

scrollBy

watch

constructor

if

Object

scrollTo

while

continue

implements

open

self

window

Date

import

opener

setInterval

with

debugger

in

outerHeight

setTimeout

FALSE

default

Infinity

outerWidth

short

TRUE

defaultStatus

innerHeight

package

static

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Review Questions 1) Which of the following are valid variable or function names: a) y b) 100percent c) a big number d) break e) subtractTwoNumbers f)

First_Name

2) Place the brackets in the correct locations indicated by the underscore. if _ z_0_ == 0 _ _ x = 2; _ 3) Complete this sentence: All statements should end in a _______________. 4) True or False. JavaScript is a case insensitive language. 5) True or False. It is a good idea to add comments to your program code. 6) Match the brackets in Column A with the use in Column B. Column A

Answer

Column B

a. { }

used for array index values

b. [ ]

used to contain a functions, arguments

c. ( )

used to contain multiple JavaScript statements

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Summary JavaScript is placed within the tags. JavaScript is very casesensitive. Although its not compulsory, not to end all statements using semicolon, as a good programming style terminate evety statement using semicolon. JavaScript ignores whitespaces. We’ll use combination of braces to make code more effective. Like other programming languages JavaScript has two different types of comments, single line comment (‘//’) and multiple line comments (‘/*…….*/’). Naming conventions has to be used for variables and function names. There are certain words are reserved as part of the JavaScript language.

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HTML, DHTML & JavaScript Chapter 17: Basic Programming Constructs In this session you will learn the basics constructs of programming. These constructs are similar in a number of programming languages, and will be used in a number of our scripts in later sessions Objectives • • • •

To declaring Variables To understand how to use Operators Creating Control Structures ( Branches and Loops ) To work with Functions ( Built-in and programmer-created)

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Declaring Your Variables A variable is a name assigned to a location in a computer's memory to store data. Before you can use a variable in a JavaScript program, you must declare its name. Variables are declared with the var keyword, like this: var x; var y; var sum; Here var stands for ‘Variant’. You can also declare multiple variables with the same var keyword. var x, y, sum; To take it one step further you can combine variable declaration with initialization. var x = 1, y = 3, sum = 0; If you don't specify an initial value for a variable when you declare it, the initial value is a special JavaScript undefined value. Remember: JavaScript is very case-sensitive so ‘x’ and ‘X’ are two different variable names.

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Types of Variables A big difference between JavaScript and other languages like JAVA and C is that JavaScript is untyped. This means that a JavaScript variable can hold a value of any data type, and its data type does not have to be set when declaring the variable. This allows you to change the data type of a variable during the execution of your program, for example: var x = 10; x = "ten"; In this example the variable x is first assigned the integer value of 10, and then the string value of the word ten.

Using Operators Operators are the things that act on variables. We have already seen an operator used in the previous example, where we were assigning values to our variables. The example used one of the most common operators, "=" or the assignment operator. Another operator would be the addition operator "+". var x = 1, y = 3, sum = 0; sum = x + y; This small chunk of JavaScript code will declare the variables x, y and sum and assign the number 1 to x, 3 to y and 0 to sum. The second line of the script will add x to y and assign it to sum. The value of the sum variable will be 4. Other operators are used to compare things, i.e. "==" equality, ">" greater than. For example, var x = 1, y = 3, sum = 0; if ( sum == 0 ) { sum = x + y; } This bit of code first checks to see if sum is equal to zero, and if so then it adds x and y together and assigns the result to sum. The "if" statement is an example of a control structure which you will examine in coming session.

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JavaScript Operators Computational These are probably the most common operators. They are used for common mathematical operations. Unary negation ( - ) Increment ( ++ ) Decrement ( -- ) Multiplication ( * ) Division ( / ) Modulo arithmetic ( % ) Addition ( + ) Subtraction ( - ) Logical These operators are very commonly used in conditional statements like "if" and "switch" that you will be learning about shortly. Logical NOT ( ! ) Less than ( < ) Greater than ( > ) Less than or equal to ( = ) Equality ( == ) Inequality ( != ) Logical AND ( && ) Logical OR ( || ) Conditional (trinary) ( ?: ) Comma ( , ) Bitwise You have probably heard that computers work with bits and bytes. These operators do work with bits or zeros and ones. These operators are very rarely used. Bitwise NOT ( ~ ) Bitwise Shift Left ( > ) Unsigned Shift Right ( >>> ) Bitwise AND ( & ) Bitwise XOR ( ^ ) Bitwise OR ( | ) Assignment It is important to note that the single equal sign is used for assignment and not for testing equality. The compound assignment operators can combine a couple of programming steps to make your code tighter, and more efficient. Assignment ( = ) Compound assignment operators Addition (+=) Subtraction (-=) Multiplication (*=) Division (/=) Training & Development Division

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Modulo Arithmetic (%=) Left Shift (=) Unsigned Right Shift (>>>=) Bitwise And (&=) Bitwise Or (|=) Bitwise Xor (^=)

Control Structures (Loops and Branches) Branches if The "if" statement is a fundamental control statement. It allows your program to perform a test, and act based on the results of that test. For example: if ( (x == 1) && (y == 3) ) { sum = y - x; } In this statement the value of the x variable is compared to 1 to see if it is equal, and the value of the y variable is compared with 3 to see if it is equal. The use of the "&&", which is the "and" operator, adds an additional logical condition that says that the first comparison must be true and the second comparison must be true for the overall result of the test to be true. If the test results in an overall true condition then the statements that follow the if statement will be executed. If the test results are false nothing will occur. An additional clause you can add to the "if" statement is the "else", an example: if (sum == 0) { sum = x + y; } else { subtotal = sum; } This statement is read as: if sum equals 0 then sum equals x plus y, or else subtotal equals sum. switch The switch statement is handy when a variable may take on a number of values and you want to test for some of those values. The use of "switch" is shorter and easier to read than a number of "if" statements. switch(n) { case 1: //start here if n equals 1. // place code here break; case 2: //start here if n equals 2. // place code here break; // stop here . Training & Development Division

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. . default; // if all other conditions fail do this // place code here break; }

Loops A loop is a programming structure that forces the statements contained within its delimiters to execute over and over again until a condition is met at which point the loop ends. While Loop The JavaScript while loop is much simpler than the for loop. It consists of a condition and the statement block. while (condition) { ...statements... } As long as the condition evaluates to 'true', the program execution will continues to loop through the statements. In the previous session, we had used the for loop to display digits 1 to 10 in an alert box. We'll now employ the while loop to do the same thing. var msg = ""; var x = 1; while (x Jani,Tove,Hege,John,Andy,Wendy join() method to put all the elements of an array into a string var arr = new Array(3); arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; document.write(arr.join() + ""); document.write(arr.join(".")); Output: -> Jani,Hege,Stale //Here separator among two array elements is ‘,’ Jani.Hege.Stale //Here separator among two array elements is ‘.’ sort() method to sort a literal array Training & Development Division

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var arr = new Array(6); arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; arr[5] = "Tove"; document.write(arr + ""); document.write(arr.sort()); Output : -> Jani,Hege,Stale,Kai Jim,Borge,Tove Borge,Hege,Jani,Kai Jim,Stale,Tove

Using the sort() method to sort a numeric array function sortNumber(a, b) { return a – b; } var arr = new Array(6); arr[0] = "10"; arr[1] = "5"; arr[2] = "40"; arr[3] = "25"; Training & Development Division

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arr[4] = "1000"; arr[5] = "1"; document.write(arr + ""); document.write(arr.sort(sortNumber)); Output : -> 10,5,40,25,1000,1 1,5,10,25,40,1000

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JavaScript Events Events are the triggers that call (start) one of your functions. Your client-side JavaScript programs will not execute (run / be interpreted) unless started by an event. An event could be an action such as clicking on a button or placing your mouse over an image. We will use the onClick event for starting our form validation scripts, and the onMouseOver event for creating graphic images that change when you place your cursor over them. The available event handlers in JavaScript are: (remember JavaScript is case-sensitive) onClick( ) A click event occurs when a button, checkbox, radio button, reset button, or submit button is clicked. This event is regularly used with a button to start script execution. In the above example when you click on the button "Click Me" it will execute the JavaScript statement "window.alert('You Clicked me');". You can call any function or method this way. onSubmit( ) A submit event occurs when the user submits a form. This event is regularly used with a form and a submit button to start the form validation script. In the above example when the user clicks on the submit button, it will execute the function "checkform()". If the form passes all the validation tests, a true value is returned and the data will be passed to the "formtest.asp" CGI program. If the form contents do not pass the validation tests, it will not send the data to the "formtest.asp" CGI program. Note: You will be using these events while using Alerts, Prompts, and Confirmations; as well as, for Form Validation. onMouseOver( ) An onMouseOver event occurs when the user positions their mouse over a hyperlink, over any object of page, or a linked region of a client-side image map. Window Loop Test Click for information of L&T Infotech. Training & Development Division

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In the above example an HTML link to a web site is created using the anchor tag. The onMouseOver() event is added to the anchor tag, and in this case the script will pop-up an alert message on the browser window. Take a look at the results below.

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onMouseOut( ) An onMouseOut event occurs when the user moves their mouse off of a hyperlink, or a linked region of a client-side image map. Window Loop Test Click for information of L&T Infotech In above example when the mouse is over the link, the hyperlink URL is shown in the status line, and when the mouse is moved off the hyperlink the message is displayed. onFocus( ) This event occurs when a user tabs into or clicks on a password field, a text field, a textarea, or a FileUpload field in an HTML form. If a user clicks on one of these elements in a form, it is receiving the user's focus. In this example when the user clicks on the month box or tabs into it a message is displayed in the status line of the browser that indicates what the user should type in.

onChange( ) The change event happens when the user leaves a password, text, textarea or FileUpload field in an HTML form, and its value has changed.

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onBlur( ) The blur event triggers when the user leaves a password, text, textarea or FileUpload field in an HTML form.

Note: It is usually a good idea to use either onChange or onBlur, and not both at the same time as they will appear to conflict with one another. onLoad( ) The load event triggers when the browser finishes loading a document or all the frame pages within a . In this example after the page has completed loading into the browser the alert message below is popped up.

onUnload( ) The unload event occurs when you move to a new document. For example if you use the back button, or click on a link to another page the unload event will occur. This example will popup the following message when someone moves off of the current page.

Note: It is possible to specify multiple events on a single HTML tag.

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For example, Window Loop Test Click me Observe the output (on Status bar), if you keep mouse cursor over the link, you will get message as:

If you keep cursor away then you will get status message as

The following table shows you what events are supported on the HTML Form Elements.

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JavaScript Events and HTML Form Elements Events / HTML Elements

Blur

Click

Button

X

Checkbox

X

Change

Focus

Load

Mouseover

Select

X

Unload

X X

Document X

Form Link

X

Radio

X

Reset

X

Selection

Submit

X

X

X

X

Submit Text

X

X

X

X

Textarea

X

X

X

X

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Review Questions 1) An object is a collection of ______________ and _______________. 2) The four objects that are built into the JavaScript language are: a) _______________ b) _______________ c) _______________ d) _______________ 3) (True or False) The DOM is a collection of objects added to the JavaScript language by the browser. 4) (True or False) Events are key to beginning the execution of your scripts. 5) Which event would you use to start a script after a page has been fully loaded by the browser? a) onClick() b) onSubmit() c) onLoad() d) onMouseOver() e) onload() 6) (True or False) Events are tied to specific HTML elements.

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Summary An object is nothing but instance of class. The new operator can be used to create objects and initialised it to some variable. To reach on any level of any specific control (it can be Form control or non-form control) Document Object Model is used. DOM contains readymade collection of objects which are helping us while finding some values or while doing certain settings. Array can be created using Array class. There are various events which are allowing us to do specific operation on particular event. There are certain built-in events like onClick, onSubmit, onMouseOver, onMouseOut, onFocus, onChange, onBlur, onLoad, onUnload etc.

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HTML, DHTML & JavaScript Chapter 19: Alerts, Prompts & Confirms Objectives • • •

To understand how to create Alerts To understand how to create Prompts To understand how to create Confirms

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Alerts, Prompts, and Confirms Alerts, Prompts, and Confirms are all methods of the window object that create predefined, popup style dialogue boxes within a window object. window.alert( message ) The "message" is plain text (not HTML) that displays in a dialog box popped up over a window. The alert box will have a button labeled "OK" that will dismiss the alert box when clicked. window.alert("Hello Gary!"); The above line of code would produce the following popup window.

window.prompt( message, default) The "message" is again plain text that will be displayed in the dialog box popped up over the window, and the default is a string that is displayed as the default input. When default is set to "", nothing will be in the prompt box. The prompt window will have an input field for the user to enter information and an "OK" button and a "Cancel" button. This method will return the value that the user types in. window.prompt('Please enter your name','Your Name'); The above line of code would produce the following popup window

window.confirm( question ) The question is another plain text string. It should be a question that you want answered by the user. window.confirm('Are you really over 21 years of age?'); The above line of code would produce the following popup window.

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If the user clicks on the OK button the method will return a Boolean value of true. If however the user clicks on the cancel button the method will return a Boolean value of false. These return values can be stored in a variable like ageTest and used with branching logic. ageTest = window.confirm('Are you really over 21 years of age?'); Our lab for this section will demonstrate using all three window methods. Let's examine the following HTML Form example: Simple Form Name:

At this point the form will do nothing when the "Submit Info" button is pressed. What we will first do is use the onClick event on the button to popup an alert message that says Hello "The name typed in" followed by an exclamation mark. Training & Development Division

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To make this button function we need to add the onClick event to our HTML page. This says when the user clicks on the button, the browser will create an alert (the popup). Alert is a method of the window object. In this case the string 'Hello ' will be concatenated with the data typed in by the user in the textbox and concatenated with the exclamation mark. Single quotes are used to delimit the strings in this example because the HTML code requires the double quotation marks as delimiters of the attribute onClick. Remember our discussion of syntax; the JavaScript statement must end with a semicolon. Refer the following example: Using Prompts, Confirms, and Alerts Using Prompts, Confirms, and Alerts Training & Development Division

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Review Questions 1. What are the predefined, popup style, dialogue boxes we can use with JavaScript? 2. Which type of dialogue box would you use if you want the user to enter some information? 3. What is concatenation?

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Summary There are certain window class’s functions which are allowing us to show alert, taking valuable opinion from users like Yes/No type question by using Confirm and taking runtime data by using prompt messages. We can use any one of these three methods to make our program more effective.

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HTML, DHTML & JavaScript Chapter 20: Form Validation

Objectives • • • •

To create a FORM with an Active Cursor To understand FORM Checking for validation To Create a function To Test form validations

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Creating a FORM with an Active Cursor When a web page, containing a FORM element, loads in the browser there is no default condition that places the cursor inside the first input element. If the user just starts to type, nothing happens because the cursor is not active, anywhere in the document in the browser. Many authors that create forms for use on the web would like to have the cursor placed and active in the first input field. It would mean that a person browsing wouldn’t have to click in the field before entering data; they could simply begin to type. FORM elements of the type text, password, textarea and file upload support, not only events such as onClick and onBlur but they also support the methods of "focus" and "blur". This means that you can tell the cursor to be placed in the input field or that it can’t be placed in specified fields. If you combine this feature with the pages onLoad event you can place the cursor in a designated field when the page loads. Simple Form Enter Cardholders Name:

Using Form Checking Form validation is accomplished by using JavaScript to preprocess the information the user types into a form before the data is sent to a CGI based server application. This practice is more efficient than allowing incorrectly formatted data to be sent to the server. If the information is incorrectly formatted you can alert the user with a pop-up and force them to correct the mistake. Form validation is one of the most common uses of JavaScript. To examine this process we expand on our FORM in our web page: Simple Form Enter Cardholders Name: Card Number: Card Expiry Date: Training & Development Division

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This form has, as much "checking" as there is available with HTML. The card number field is restricted to 16 characters, but does not require 16 at this point. Our month and year fields are broken into two text areas that will only allow two characters each, but do not require two. The script must check: 1. To make sure a name is entered into the Cardholder's Name field. We will test this by making sure the user has typed in at least one character. 2. To make sure the card number is 16 characters long, and is made up of only numbers. We will do this by testing the length of the string typed in by user, and testing to make sure that it is only made up of numbers. 3. To make sure the month and year are entered as numbers, and that they are valid. This means the month must be between 1 and 12 and the year must be greater than or equal to this current year. 4. If any of these criteria are not met then an alert should notify the user of what is wrong, and the information should not be sent to the server for processing. Let’s start by adding your required script tags and comments; as well as, creating a new function called checkform. The function checkform() does not currently have any instructions to execute. We will add these shortly. In order to call this function we will add the following onSubmit event to the FORM HTML tag. onSubmit="return checkform();" Training & Development Division

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Now when someone clicks on the Submit Info button it will first execute the checkform() function before sending the information to the web server for processing. Note that we are using the "return" property, associated with the "checkform" function, which looks for a value of true or false from the associated function. If checkform() returns a value of true, then the form contents will be submitted to the Server side Script, on the server, for processing. If checkform() returns a value of false the contents will not be submitted and some other action may be initiated such as an alert. The next piece of code you will add is a string variable named "message" that will hold the contents of the error message to be displayed to the user as an alert. You will also add an "if" structure that will test for the length of the error message. If the "message" variable's length is greater than zero then an alert message should be displayed, if it is zero then the information is correct and should be sent to the server for processing. Now you have this structure in place, now you can create your first real test of your form. Lets check to see if the length of the card holder's name is greater than zero. if (document.CardForm.HoldersName.value.length == 0) { message = message + "Please enter the name on the credit card!\n"; } This statement appears complex at first, but lets step through it to see how it works. The "if" is testing the value typed into the HoldersName field of your HTML FORM named CardForm that is in the document. This accurately references the object’s value, the .length will return the length of the number of characters in the string. If the length is equal to zero you know that the user has typed nothing in, and you should create an error message. Creating the error message is the purpose of the next line. The error message you want to display is "Please enter the name on the credit card!". The \n at the end of the line will cause a carriage return and a linefeed so that the next error message will display on a new line inside the same alert box. You know that you will be testing each field for a correct value so we may have a different error message associated with each test. You add the current value of the message variable using the (+) concatenation operator and store the result back in the message variable using the (=) assignment operator. You can now add the next three tests that are all the same structure. Note: You will notice that we have added comments to some of the code. This is great for remembering what something is doing down the road. Commenting also makes it easier for others to understand your code. if (document.CardForm.CardMonth.value.length < 2) { // test to make sure two characters where entered message = message + "Please type in both digits of the expiry month!\n"; } else if (isNaN(document.CardForm.CardMonth.value)) { // test for numeric digits only message = message + "The Month value needs to be between 1 and 12\n"; } else if (document.CardForm.CardMonth.value < 1 || document.CardForm.CardMonth.value > 12 ) { // test the values to make sure they are not less than 1 or // greater than 12 message = message + "The Month value needs to be between 1 and 12\n"; }

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The above code segment is built upon our length test. Now that you know you have two characters you must check to see that they are numeric. Once that has been determined you need to check to make sure the numeric values are within the range we are interested in. We use a new function in the code segment; isNaN(), which means " is Not a Number". “isNaN()” will return a value of true if the string being evaluated is not a number, or it will return a value of false if the string being evaluated is made up of only numeric digits. We use the operators < "less than", > "greater than", and || "or". So the last expression is read as follows; "if the value is less than one or greater than 12 then display an error message." Once you have added this code to your web page, you can test all of the conditions with the following inputs: blank, aa, 1, -1, 13, and 06. Then we add similar lines to setup the test for a valid year. Use 99, 98, 00 for test values. As you can tell, your script is not year 2000 compliant. Add the necessary lines to test for 16 digits in the card number. Test with the following inputs: 123456789abcdefg, 123456789, 1234567890123456. Complete Script Simple Form Enter Cardholders Name: Card Number: Card Expiry Date: /

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Review Questions 1. What event was used to place the cursor in the first field of our FORM? 2. What did we test to see if the user had entered any information into any of the fields? 3. What does the "return" operator do? 4. How do we get the next error message to appear on the next line down? 5. What function is used to verify that certain entries are numbers?

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Summary We can create a FORM with an Active Cursor by using focusing mechanism. To do the validation, especially on client side JavaScript is very useful. By using proper combination of functions, form check we can do validation in JavaScript. Once validation gets over we have to test validation for all possible combinations.

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HTML, DHTML & JavaScript Chapter 21: Mouse Over Effects In this module you will create a very flexible and robust script that you can use over and over again to create mouse roll over effects. Objectives • • • • •

Understanding the image object Learning Mouse-over effects To create flexible functions Understand how to pre-load images To work with eval function

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Image Object When you add the HTML tag to your web page you are creating an image object. For example: The image objects on your page can be referenced as an array, where document.image[0] refers to the first image on the page, and document.image[1] the second and so on. If you add the NAME attribute to the tag we can use the value of the NAME attribute to reference the image object. For example: This image object can be referenced as document.image['mouse1']. Remember that JavaScript is case sensitive and "mouse1" is different from "Mouse1" or "MOUSE1". The generic syntax you will be using in this section is: document.images['imagename'].property = newvalue; The image object has the following properties: border This value can only be read, and is the width of the border around the image specified in pixels by the BORDER attribute. complete This value can only be read, and is a Boolean value that will let you know if the image has completed downloading (true) or not (false). height This is a read only value that specifies the height in pixels of image set by the HEIGHT attribute. hspace This is a read-only value, and refers to the space on the right and left of the image specified in pixels by the HSPACE attribute. lowsrc This is a read/write string that specifies a URL of an alternate image. The image should be suitable for display at low resolutions; it is specified by the LOWSRC attribute. name This is a read-only value, specified by the NAME attribute. As you will see it is a good idea to name your images. src This is a read/write string that specifies a URL of the image. vspace This is a read-only value, and refers to the space on the top and bottom of the image specified in pixels by the VSPACE attribute. width Training & Development Division

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This is a read only value that specifies the width in pixels of image set by the WIDTH attribute. Since we can read and write to the src property, we can change the image that is displayed in the browser. This is what allows us to create mouse roll-over, sometimes called hover buttons, when used in combination with the element in creating links.

Mouse-over In the mouse rollover script that we will create, we will be changing the src property of the appropriate image object when the onMouseOver and onMouseOut events are triggered. We will start with a very basic and simple implementation and then add to it to make it more flexible and powerful. To create the effect we need two graphic images that are generally the same with a little bit of difference for example mouse_out.gif and mouse_over.gif, both located in the \gifs subdirectory of your student files.

The following HTML page codes with the addition of the JavaScript events will change the image when the user positions their mouse over the image and change it back again when they move their mouse off the image. The image is originally set to the mouse off image using the tag. Mouse Over and Mouse Out Creating Flexible Functions To improve our mouse over script we want to start by creating two functions. One that will be called when the mouse is on the image, and one that is called when the mouse is off the image. Web Page containing JavaScript As you can see in the above code you have added two functions that do the same thing as the inline script did in the previous example, and you have changed the event triggers to call your new functions. This provides you with the flexibility to apply your function to different images. Next we want to add an argument to our functions so that they will accept the name of the image we want to change. We will then combine the image name with a standard file extension to make our function work for any number of buttons. Web Page containing JavaScript In this example we pass the value "mouse1" or "mouse2" to our functions. This value in turn gets stored in the variable "imageName". Next we want to focus our attention on the string that is equated to the image name. The string "gifs/mouse_out.gif" is not very flexible. We need to express that as: "gifs/" + imageName + ".gif" The line above will create the correct string value for each set of images to change. At this point we will need four (4) graphic images; mouse1_over.gif, mouse1_out.gif, mouse2_out.gif and mouse2_over.gif. Web Page containing JavaScript Although the above example will work and create the flexibility that you require, it is not optimized. When the browser loads this page it only loads the two mouse out images. When the user positions the mouse over the image for the first time the browser must download the mouse over image. This can be slow and your effect will not display properly. The solution is to pre-load all of your images into the browser's cache so that they can be accessed quickly.

Pre-loading Images In previous example we had only two image objects mouse1, and mouse2 respectively. We are going to create four more, and pre-load them into our browser's cache. You can pre-load all four of your images files in to the browser's cache by creating four new objects mouse1_on, mouse1_off, mouse2_on, mouse2_off. These image objects are not displayed in the browser. You will be using them to hold the images so that you can quickly switch between them. Let's look at an example of how to do this: var mouse1_off = new Image(); mouse1_off.src = "gifs/mouse1_out.gif"; var mouse1_on = new Image(); mouse1_on.src = "gifs/mouse1_over.gif" For each image file, we create a new image object, and set its src attribute to the appropriate filename. In setting this property, the browser decides it needs to download the image file, at which point it is stored in the cache for quick retrieval, when it is called for display. Our page will now contain six image objects: mouse1, mouse1_on, mouse1_off, mouse2, mouse2_on, and mouse2_off. To make the image change in the browser you need to make the src attribute of the image object created by the tag in our case mouse1 or mouse2 equal to on objects src or the off objects src. You can reference the two image objects created by the HTML tag as follows: document.images['mouse1'] or document.images['mouse2'] We want to be able to set those images src attribute equal to one of the other objects src attributes. Training & Development Division

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document.images['mouse1'].src = mouse1_on.src or document.images['mouse1'].src = mouse1_off.src Notice in the above example, to make it work for mouse2 you would just have to substitute mouse2 for mouse1. So for your function we will substitute the mouse1 reference with a variable called imageName. document.images[imageName].src = imageName + "_on.src" or document.images[imageName].src = imageName + "_off.src" From earlier in the course you will know that JavaScript is going to try to concatenate (join) the string value of the imageName variable with the other string component to form the object name mouse1_on.src or mouse1_off.src. If you tried to do it this way it wouldn't work because what the JavaScript interpreter would be trying to make the src parameter equal to mouse1_on.src for example. This appears to sound ok, except the src parameter is expecting a URL for the image, NOT a string. To get around this you will us a special function in JavaScript called eval(). eval() We place the eval function around the concatenation like so: document.images[imageName].src = eval( imageName + "_on.src" ); The order of operations that is followed this time is that the value of the imageName variable is concatenated with the string, to form one string like mouse1_on.src. The eval function then converts that to JavaScript code, meaning that it converts to the reference to the object we created in our preloading phase and it's src parameter. This way we are making the src parameter of one object equal to the src parameter of another image object. This effectively flips the object in the browser. Your new script looks like this: Web Page containing JavaScript

Testing for completion and compatibility You should add two more pieces to your script, a test to make sure the image is completely downloaded and to make sure that the browser supports the image object. You will start by testing for completion. function MouseOn(imageName) { if( eval(imageName + "_on.complete") ) { Training & Development Division

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document.images[imageName].src = eval( imageName + "_on.src" ); } } //end function MouseOn You want to use the image object's complete property to test to see that the image has been completely downloaded before you try to change to it so the user will never see a partially loaded image. Similar to the use of the eval in the previous section, here we want to combine the value of the imageName variable with the string "_on.complete" to create the complete image name and property, and have JavaScript act on the object instead of the string. Next you will test for compatibility. You can do this very simply by testing the browser to see whether it supports the image object. Earlier browsers like Microsoft Internet Explorer 3.0, and earlier did not support this object. To make your code browser proof you will add this conditional statement to your code. if (document.images) { // if browser supports images …do stuff… } You need to add this to both of your functions, and to the pre-loading piece of your code. Completed Script Web Page containing JavaScript

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Review Questions 1. What two events are used to create the mouse roll-over effect? 2. What properties of the image object can you read and write? 3. Which property is a Boolean value you can test for? 4. Why do we pre-load our images? 5. Why is it important to test to see if the images have completely downloaded? 6. What would you need to add to our script to get it to work with more than two links?

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Summary We can use the image object to work with images inside javaScript files. Use the onMouseOver, and onMouseOut events to do specific operations. Here we can create a flexible mouse rollover function. Pre-loading of our images is required so that after loading images thogh there is no connection then we can still work with those images. The eval function is used to evaluate arithmetic expressions. We have to test for image download completion and browser compatibility so that we can start working with Images.

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HTML, DHTML & JavaScript Chapter 22: Pop-Up Windows

Objectives •

• •

To create Pop-up windows o Using window.open method o Using window.close method Explaining the window features To set the document colours

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Pop-up Windows In this chapter you are going to use the window object and the open and close methods. This particular programming technique can be put to good use or it can be misused. A good use is to highlight a product a customer may be interested in. window.open( URL, Name, Features, Replace ) Arguments: URL the URL of the document to be displayed in the new window. Name an optional string that specifies the name property that can be used with the target attribute. Features is a comma-separated list of features about the window; alwaysLowered, alwaysRaised, channelmode, dependent, directories, fullscreen, height, hotkeys, innerHeight, innerWidth, left, location, menubar, outerHeight, innerWidth, resizable, screenX, screenY, scrollbars, status, toolbar, top, width, z-lock Replace Optional boolean argument, that states weather the page that gets loaded gets added to the page history in the browser. This argument was intended for use when changing the contents of a window. window.close() This method allows the user to close a window. Window Features Explained When you create a new pop-up window you will need to turn off any window features that you do not want displayed in the window. As well, you will need to set the size of your new window. status (status bar): the line at the bottom of the browser that displays information. To display a window with no status bar, set status=no.

location: shows the URL of the page you are looking at. To turn the location bar off, location=no.

toolbar: contains the buttons you use to move through history (back, and forward) to stop web page loading, etc. To display a window with no toolbar, set toolbar=no

menubar: is the bar that has all of the drop down menus. To turn the menubar off, menubar=no.

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scrollbars: are the sliders on the right hand side and bottom of a window that let you move up or down and left or right. To turn off the scrollbars, scrollbars=no. left, and screenX: control the window's position from the left of your screen in pixels. Left is used by Internet Explorer and screenX is used by Navigator. top, and screenY: control the windows position from the top of your screen in pixels. Top is used by Internet Explorer and screenY is used by Navigator. height: is the height of the window in pixels. width: is the width of the window in pixels. The following feature string sets the height to 500 pixels, width to 400, and turns off the menubar, scrollbars, status line, and the toolbars, and positions the window at the top of the screen one hundred pixels from the left of the screen. window.open('height=500,width=400, menubar=no, screenX=100,screenY=0,left=100,top=0')

scrollbars=no,

status=no,

toolbar=no,

It is very common to see popup windows displayed with all of the features turned off. We will start with your fairly standard HTML page: JavaScript Popup Window

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To the function popupwin() we will add the following line of code: winpopup = window.open('latestNews.html', 'popup', 'height=500, width=400, scrollbars=no, status=no, toolbar=no, screenX=100, screenY=0, left=100, top=0');

menubar=no,

This line will create a new window, and load the file latestNews.html into that window. The name of the window is set to "popup". The window will have the following features: •

500 pixels high

•

400 pixels wide

•

no menubars

•

the scrollbars

•

a status line

•

the toolbars

The window will also be located zero pixels from the top of the screen and 100 pixels from the left of the screen. Remember, Microsoft Internet Explorer uses the left and top features, while Netscape Navigator uses screenX and screenY. If you open up the file latestNews.html you will notice that we used a similar structure to create a close window button. JavaScript Popup Window You called! Training & Development Division

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Creating the windows contents on the fly You can modify your script to create the document that will appear in your new window instead of displaying a pre-made document as we did previously. The first thing you need to modify is the window.open statement so that it does not load a particular page. We can accomplish this by replacing the file 'latestNews.html' with a single double quote mark, as illustrated: winpopup = window.open('','popup','height=500,width=400, menubar=no,scrollbars=no,status=no,toolbar=no, screenX=100,screenY=0,left=100,top=0'); To create the actual HTML page that will appear in our pop-up window you need to use the document.write() method. This method allows you to write text to the specified document. For example: winpopup.document.write('\n\n'); This line will start the creation of your HTML document in the window identified by the winpopup window object. You would need to create the whole HTML document like this. For example: winpopup.document.write('\n\n'); winpopup.document.write('This is a popup\n'); winpopup.document.write('\n'); winpopup.document.write('\n'); winpopup.document.write('\n\n'); This will create an empty document in the new pop-up window. When you are finished writing information to the new window you should let the browser know that nothing more is coming, you can do that with the document.close() method which would be added after the lines above. Your code should look like this: function popupwin() { winpopup = window.open('','popup','height=500, width=400, menubar=no, scrollbars=no, status=no, toolbar=no, screenX=100, screenY=0, left=100, top=0'); winpopup.document.write('\n\n'); winpopup.document.write('This is a popup\n'); winpopup.document.write('\n'); winpopup.document.write('\n'); winpopup.document.write('\n\n'); Training & Development Division

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winpopup.document.close(); //Close the Window to additional writes } //end function popupwin()

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Now that you have the window opening and displaying an empty HTML page you should make it do something a little more creative. You want your pop-up window to thank your customer for purchasing a product. To start you need to add a text input field to your form. Please enter your name: This will create a page that looks like this:

To get "Mr. JavaScript" to display in your window you need to add the following line to your script: winpopup.document.write('Thank you, '+ document.FORM1.YourName.value + ' for choosing XYZ Product\n'); This line will combine the strings with the value typed in by the user, and should be located in your script between the lines that write the BODY tags. You should also give the user, the ability to close this newly created pop-up window. To accomplish this you will add the following lines after the one above. winpopup.document.write('\n'); winpopup.document.write('\n'); winpopup.document.write('\n'); This will create a button called "Close Window" that when clicked will close the current browser window.

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Setting the document colors When you use popup windows there are some additional properties you may want to control. The document object has properties that allow you to set the document's background color and the default color for text in the document. The background color can be changed at any time. This allows you to create some interesting effects in your popup window. The text color can only be set once after the body tag has been written to the document (see the completed code). An example of using these properties is below. //set the documents background color winpopup.document.bgColor = "#0000FF"; RRGGBB //set the documents text color RRGGBB winpopup.document.fgColor = "#FFC814"; Complete Script JavaScript Popup Window

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Review Questions 1. What are the two methods used with popup windows? 2. What are some good uses of popup windows? 3. (True or False) You can not control the size of a popup window. 4. (True or False) It is not common to see popup windows displayed with all of the features turned off.

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Summary We can create pop-up windows by using JavScript. In that case we can use the window.open method to open the window and can use the window.close method to close the specific window. There are various features associated with windows by which we can make required designments.

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HTML, DHTML & JavaScript Chapter 23: Cookies

Objectives • • • •

To understand cookie Understanding how to save a JavaScript cookie To Retrieve a JavaScript cookie Understanding how to delete cookies

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Introduction to cookies A cookie is simply a variable that your webpage can store on or retrieve from the user's computer. The idea is that the next time the user arrives at your page, the value of the cookie can be read by your page, and then used for whatever purpose you choose. Examples of cookies could be: •

First time the visitor arrives the name is entered. (for example "Sam Smith"). The username is then stored in a cookie. Next time he arrives at your page, it writes something like: "Welcome to my page Sam Smith!! Good to see you again". The name is simply retrieved from the stored cookie.

•

First time the user arrives at your page she enters the desired language. The chosen language is stored in a cookie. Next time she visits your site, she will simply be taken to the pages in the desired language without asking, since the desired language is retrieved from the cookie.

•

First time the user arrives at your page he is asked to fill in a password. The password is saved in a cookie. Next time he arrives at your page, the password is retrieved from the cookie.

Cookie Limits Users have good reason to be wary of force-fed cookies from strange servers. It is important to note, however, that the potential for abuse is limited in the following ways: • The file that maintains the cookie on the client machine may contain not more than 300 individual cookies. • Whenever a new cookie is saved to a file that is at the 300-cookie limit, the least recently accessed cookie is deleted. • A single site may post not more than 20 cookies to any client’s file • Individual cookies may be no larger than 4 kilobytes (including ID information placed in the cookie by the browser).

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What is a cookie anyway? A cookie is a small piece of information stored by the web browser on the client machine in a text (.txt) file which can be retrieved later. A script/program either on server side or client side may request the web browser to store a cookie. Cookie information is stored as a name value pairs. JavaScript provides document.cookie property for manipulation of a client-side cookie. One can set the cookie property at any time. Cookies can be very useful for •

State Maintenance/Persistence across different pages of the site, for HTTP is a state less protocol. In english, it means cookies can be used for "remembering" certain data specific to the user (such as User ID) as he browses different pages of the site. Session variables used in server side scripts such as ASP make use of cookies for this purpose.

•

To allow user-side customization of web information, to serve a personalized site, as done by Yahoo and few others.

A cookie can be sent back only to the server which created it. Thus, allowing a two way communication of a cookie. Many web servers use this to store user preferences, user ID on the user machine; which are sent back to them when user revisits the same site. This information can then be used by the web server to enhance and personalize the user experience. The cookies are stored and sent by the webbrowser, provided that it is cookie enabled. Usually, cookies are pretty safe and most sites use them widely. Moreover, most sites will not work as desired if you disable cookies.

How do we use cookies? As you must have noticed by now, the important steps in cookie manipulation are •

Create A Cookie - Create or set a cookie on user machine having cookie name, cookie value and the time when cookie should get deleted automatically (EXPIRES atribute, this is optional). If this is not specified the cookie is called a session cookie and it expires (gets deleted) when user's session ends, i.e. when the browser is closed. The additional information that can be optionally stored in the cookie includes (1)Path, (2)Domain, (3)Secure. Secure is used only over a secure communication channel ( currently only HTTPS).

•

Read The Cookie - Read the stored cookie and extract its value. This requires only cookie name. Remember that you can only read the cookie which is created by your script/program.

•

Delete The Cookie - This may not be always done, as expires attribute takes care of it. To delete a cookie set/create a cookie with the exactly same PATH (if any) and NAME values, and an EXPIRES value which is in the past.

The JavaScript code here lets you manipulate cookies by using three functions to do above mentioned tasks. For creating a cookie, for reading a cookie and for deleting a cookie. The function prototypes and usage •

function setCookie(szName, szValue [,szExpires] [,szPath] [,szDomain] [,bSecure]) - To create/set a cookie. It requires at least two arguments szName and szValue, and 4 optional arguments 1. szExpires - A Date object specifying the date on which the cookie expires. 2. szPath - A string argument specifying path, / is the common value. 3. szDomain - A string argument specifying the domain attribute for this cookie.

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4. bSecure - A boolean value (true/false), if this cookie is meant for communication over a secure channel, for HTTPS cookies only. This function creates a cookie string from the given arguments (by URL encoding name=value attributes), and sets the cookie as document.cookie = szCookieText; //constructed cookie string •

function getCookie(szName) - To read the cookie set by setCokie(...) function. The only argument which it takes is the cookie name szName, which is set by the previous function. This function returns the cookie value read, which can be parsed if necessary, to get the required data. This function simply parses document.cookie for the given cookie name, and returns the extracted cookie value in the original format (by URL decoding the value).

•

function deleteCookie(szName) - You can use this function optionally to delete the cookie. It takes only one parameter cookie name, szName and deletes the cookie immediately. This function simply sets the same cookie with an expires attribute which is in the past, thus deleting it immediately irrespective of the original expires attribute.

You can include these functions in your HTML file(s), to create and read cookies easily by calling these functions without any modification. Cookies – The Complete Example Cookies Demo Training & Development Division

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Cookies Demo //for creating a cookie setCookie("firstName", "Sam", nextMonth); This will set a cookie named 'firstName' with value 'Sam' on the user machine which expires one month after its creation. It uses only 3 arguments of the available 6 ones. //for reading the cookie var szName = getCookie("firstName"); alert(szName); In this code snippet, the variable szName will contain the value of the cookie named 'firstName' which has been set earlier. This variable can be later used as required. In your case //for deleting the cookie deleteCookie('firstName'); It simply calls the deleteCookie() function with the cookie name 'firstName' to delete the cookie.

Final Words about Cookies Although cookies are very useful for all these reasons and perhaps more, here are few things you should know. •

The browser or user can delete cookies before it expires.

•

Many people can share one machine and one person can use multiple machines, so cookies are not always reliable completely.

•

Do not rely only on cookies for state maintenance/persistence, support it with server side as well.

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•

Do not store sensitive information in cookies.

•

Do respect user privacy.

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Review Questions 1. A variable that your webpage can store on or retrieve from the user’s computer is known as ___? a. Java b. Cookie c. Applet 7. The best time to read a cookie is a. b. c. d.

onBlur onLoad onSelect onChange

8. The expiration date is stored in a cookie as a. A GMT string b. A Date data type c. A digital sequence type d. A sequential numeric type 9. State True of False. Your JavaScript actually writes a cookie to a visitor’s hard disk if you set an expiration date for the cookie. a. True b. False 10. A cookie takes the format of a ____________ a. Pair-name value b. Pair-value name c. Value-name pair d. Name-value pair

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Summary A cookie is simply a variable that your webpage can store on or retrieve from the user's computer. Cookies can be use in application like showing visitor counter, welcome user based on previous visits, setting default language so that it will not ask next time. We can have maximum 20 cookie pages on per client machine. The maximum size of individual cookie file cannot exceed more than 4 Kilo Byte. After creating cookies depends on requirements either you can read cookie values or can delete cookies. Its advisable to create different functions to write cookie, read cookie and delete cookies.

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HTML, DHTML & JavaScript Chapter 24: Document Object Model

Objectives •

To understand objects in Document Object Model

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JavaScript Objects Reference History Object The History object is predefined object which can be accessed through the history property of the window. The History object consists of an array of URLs. These URLs the user has visited within a browser window. Properties Syntax: history.Property_name Property length Methods Syntax: history.Method_name() Method back() forward() go(number/ “URL”)

Description Returns the number of elements in the history

Description Loads the previous URL in the history list(same as clicking The back button and to history. go (1) Loads the next URL in the history list (same as clicking the Forward button and to history. go (1) Loads a specified URL from the history list

Navigator Object The Navigator object contains information about the client browser. The Navigator object’s collection, properties and method are described below: Collections Collections plugins[] Properties Syntax: object. Property_ name Property appCodName appMinorVersion appName appVersion browserLanguage cookieEnabled

Description Returns a reference to all embed object in the document

platform systemLanguage userAgent

Description Returns the code name of the browser Returns the minor version of the browser Returns the name of the browser Returns the platform and version of the browser Returns the current browser language Returns a Boolean value that specifies whether cookies are enabled in the browser Returns the CPU class of the browser’s system Returns a Boolean value that specifies whether the system is in offline mode (In 4+ the user can choose to work offline by Selecting file/work offline in the browser. When work offline is selected, the system enter an offline state, and content is read from the cache) Returns the operating system platform Returns the default language used by the OS Returns the value of the user-agent header sent by the client to

userLanguage

Returns the OS natural language setting

cpuClass onLine

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Methods Syntax: object.method_name() Method Description javaEnabled() A Boolean value that specifies whether the browser has Java enabled taintEnabled() A Boolean value that specifies whether the browser has data tainting enabled

Document Object The Document object is used to access all elements in a page. The Document object’s collection, Properties, methods, and events are described below: Collection Collection Description anchors[] Returns a reference to all anchor object in the document applets[] Returns a reference to all applet object in the document attributes[] childNodes embeds[] Returns a reference to all embedded object in the document forms[] Returns a reference to all from object in the document images[] Returns a reference to all image object in the document links[] Returns a reference to all Link object in the document plugins[] sylesheets[] Properties Syntax: document.Property_name Property alinkColor bgColor body cookie documentElement domain fgColor lastModified linkColor referrer

URL vlinkColor

Description Sets or returns the color of the active link in the documents Sets or returns the background-color of the documents Specifies the beginning and end of the documents body Sets or returns all cookies associated with the document Returns a reference to the root node of the documents Return the documents server’s domain name Sets or returns the text-color of the document Returns the date and time the document was last modified Sets or returns the color of the links in the documents Return the URL of the document that loded the current document Returns the title of the document (text inside the HTML Title elements Returns the URL of the current document Sets or returns the color of the visited link in the document

Methods Syntax: documents.Method_name() Method clear() close() createAttribute(“name”) createElement(“tag”) createTextNode(“txt”) focus() getElementById(“id”) getElementsByName(“name”) getElementsByTagName(“tag”) open(“mimetype”[,replace])

Description Clears all elements in the document Close the output stream and display the sent data Creates an attribute with a specified name Creates an element Creates a text string Gives the document focus Returns a reference to the first object with specified ID Returns a collection of object with the specified NAME Returns a collection of object with the specified TAGNAME Open a document for writing. If a document exist in the targ-

title

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write(“str”) writeln(“str”)

et itwill be cleared. If this method has no arguments, a new Window with about: blank is displayed. Writes a text string to a document opened by open() Writes a text string followed by a new line character to a Document opened by open()

Events Syntax: document.event-name=”someJavaScriptCode” Event Description onClick Executes some code when onDblClick Executes some code when onFocus Executes some code when onKeyDown Executes some code when onKeyPress Executes some code when onKeyUp Executes some code when onMouseDown Executes some code when onMouseMove Executes some code when onMouseOut Executes some code when onMouseOver Executes some code when onMouseUp Executes some code when onResize Executes some code when

a click event occurs a Doubleclick event occurs a focus event occurs a Keydown event occurs a KeyPress event occurs a KeyUp event occurs a Mousedown event occurs a Mousemove event occurs a Mouseout event occurs a Mouseover event occurs a Mouseup event occurs a Resize event occurs

Example: functions getElement () { var x=document.getElementByld(“myHeader”); alert(“I am “ + x.tagName + ”element”) }

Window Object The Window object corresponds to the browser window. A Window objects is created automatically with every instance of a or tag The Window object’s collection, object, properties, method, and events are described below: N: Netscape (including Mozilla when N6 or higher), Internet Explorer Collection Description frames[] Returns all named in the window Object Object clientInformation document event external history location navigator screen Properties Syntax: window.Property_name Property closed Training & Development Division

Description Contains information about the browser Represents the HTML document object in the window Represents the state of an event Contains the URL visited from the window. Contains the current URL of the window. Contains information about the browser. Contains information about the client’s screen

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defaultStatus dialogArguments dialogHeight dialogLeft dialigTop dialogWidth frameElement length name offscreenBuffering opener parent returnValue screenLeft screenTop self status top Methods Syntax: window.Method_name() Method alert(“msg”) attachEvent(“event”;pointer) blur() clearInterval(ID)

referenced window has been closed Sets or returns the default text in the statusbar of the Windows(will be displayed when the page loads) Returns all variables passed into the modal dialog Window. Sets or returns the height of the modal dialog window Sets or returns the left coordinates of the model dialog Windows Sets or returns the top coordinates of the model dialog Window Sets or return the width of the model dialog window Return the frame/iframe object that is hosting the Window in the parent document Sets or returns the number of frames in the window Sets or returns the name of the window Sets or returns a Boolean value that specifies whether The window is drawn offscreen before being visible To the user Sets or returns a reference to the window that created the window Return the parent window Sets or returns the value returned from the model dialog Window Returns the x-coordinate of the upper left corner of the Browser relative to the upper left corner of the screen Returns the y-coordinate of the top corner of the browser -relative to the top corner of the screen Returns a reference to the current window Sets or returns the text in the statusbar of the windows Returns the topmost ancestor window

Description Displays an alert box with a massage and an OK button Removes focus from the current window Cancels a timeabout that is set with the setInterval() Method

clearTimeout(ID)

Cancels a timeabout that is set with the setInterval() Method

close() confirm(“msg”)

Closes the current window Displays a dialog box with a massage, a cancel, and an OK Button

createPopup([args}) execsScript(“code”;”lang”)

Creates a pop-up window Executes a specified script. The arguments can take the Following values:

focus() Training & Development Division

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moveBy(x,y)

Moves the window a specified number of pixels in relation to its current co-ordinates

moveTo(x,y)

Moves the window’s left and top edge to the specified coOrdinates

navigate(“URL”) open([“URL”,”name”,”specs”, replace])

Load the specified URL into the windows

print() prompt([“msg”,”default”])

Prints the content of the current window Displays a dialog box prompting the user for in put. The Argument can take the follows values; msg

resizeBy(x,y) resizeTo(width,height) scrollTo(x,y) setActive() setInterval(code,millisec[,”lang”])

setTimeout(code, millisec[,”lang”])

showHelp(“URL”[,contextID])

showModelDialog(“URL”[, args, “list”])

Optional. The massage to display in the dialog box. Default is default Optional. The Default text in the input field Resizes the windows by the specified pixels. Note: This method does not work on dialog windows Resizes the windows by the specified width and height. Note: This method does not work on dialog windows Scrolls the content to the specified co-ordinates Calls a function /evaluate an expression every time a specified interval(in milliseconds) has been reached. The argument can take the following values: code Required. A pointer to a function or the code to be executed millisec Required. The number of milliseconds lang Optional. JScriptVBScript JavaScript Calls a function /evaluate an expression after a specified number of Milliseconds. The arguments can take the following values: Required. A pointer to a function or the code to be executed code D millisec Required. The number of milliseconds lang Optioanal. JScript/ VBScript/ JavaScript Displays a Help file (must be of type .htm or chm). When using this Method , a second Help box appears when pressing F1 OR when clicking Help on the menu bar. To prevent the default help box from appearing set return Value to false. The argument can take the following values URL Required. The URL of a Help file contextID Optional A string or integer that specifies a context identifier Fier in the Help file Loads a URL in a model dialog box. A model dialog box retain focus while open. The user CANOT switch windows until the dialog box is closed. The argument can take the following values: “URL”- Required. The URL of the document to display. args-Optional. The argument to use when displaying the URL. Use this parameter to pass a value of any type, including an array of value. The dialog box can extract the values from the dialogArguments property of the windows object. “list” –Optional. Specifies the windows ornaments for the dialog box,

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Using one or more of the following semicolon-delimited values: dialogHeight : number dialogLeft :number dialogTop : number dialogWith : number center : yes| no |1| 0 |on |off edge : sunken | raised help :yes | no |1 | 0 on |off

showModelessDialog(“URL”[, args,”list”] )

the height*of the dialog window the left position of dialog windows the top position of dialog windows the width* of the dialog windows whether to center the dialog window within the desktop. Default is yes the edge style of the dialog window. Default is raised whether the dialog windows display the Help icon. Default is yes

Resizable :yes |no | whether the dialog window is resizable. Default 1 | 0 | on | off is no SCROLL : yes | no | 1|whether the dialog window displays a scrollbars 0 | on | off Default is yes Status whether the dialog window displays a status bar. Default is yes for untrusted dialog windows and No for trusted dialog windows For menus and Help systems). The arguments can take the following Values: “URL”-Required. The URL of the document to display. Args – Optional. The argument to use when displaying the URL. Use This parameter to pass a value of any type, including an array of Values. The dialog box can extract the values from the dialog Arguments property of the window object. “list” – Optional. Specifies the window ornaments for the dialog box.

Events Syntax: window.Event_name=”someJavaScriptCode” Event Description onBlur Executes some code when a Blur event occurs onError Executes some code when an Error event occurs onFocus Executes some code when a focus event occurs onLoad Executes some code when an Load event occurs onResize Executes some code when a Resize event occurs onUnload Executes some code when an Unload event occurs Examples of window Object Ex.1: function timeout() { setTimeout(“alert(‘This alert box popped up 1 second after you clicked the button’)”,1000); } Ex.2: function timeout() { Training & Development Division

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window.setTimeout(“change_text(document.All(‘t’)”,3000); } function change_text(tid) { tid.style.color=”red”; }

Form Object From are used to prompt users for input. We may use form elements such as text fields, radio buttons, check boxes and selection lists. The input data is normally posted to a server for processing. The From Object’s collections, properties, method, and events are described below: Collection Collection elements[] Properties Syntax: object.property_name Property acceptCharset action encoding enctype id length method name tabIndex target

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Description Returns an array containing each element in the form

Description Sets or returns a list of character encoding for form data that must be accepted by the server processing the form Sets or returns the URL of the input data will be submitted Sets or returns the MIME encoding for the form Sets or returns the MIME encoding for the form Sets or returns the id of the form (In IE 4 this property Is read-only) Returns the number of elements in form Sets or returns how form data is submitted to the server (“get” or “post”) Sets or returns the name of the form Sets or returns the index that defines the tab order for the form Sets or returns the target window of frame that responses are sent to after submission of a form

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Methods Syntax: object.method_name() Method reset() submit()

Description Resets the default values of elements in the Form(same as clicking the Reset button) Submit the form (same as clicking the Submit button)

Events Syntax: object.event_name=”someJavaScriptCode” Event Description onReset Executes some code when a Reset event occurs onSubmit

Executes some code when a submit event occurs

Location Object The Location object contains information about the current URL. Note: The location object is not W3C standard. The Location object’s properties and method are described below Properties Syntax: object.property_name Property hash host hostname href pathname port protocol search Methods Syntax: object.method_name() Method assign(“URL”) reload(false|true) replace(“URL”)

Description Sets or returns the part of the href property that follows the hash sign (#) Sets or returns the hostname and port number of the location or URL Sets or returns the hostname of the location or URL Sets or returns the entire URL Sets or returns the file name or path specified By the location object Sets or returns the port number associated With the URL Sets or returns the protocol part of the URL Sets or returns the part of the href property that follows the question mark (?)

Description Loads a new document Reloads the current document Replaces the current document with the one specified

Image Object The image object represents an HTML img element. For each instance of an HTML tag in document an image object is created The Image object’s properties and events are described below:

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Properties Syntax: object.property_name Property align

Description Sets or returns how to align the image According to the surrounding text

alt

Sets or returns an alternate text to write if The image cannot be displayed

border

Sets or returns the width of the border of the Image in pixels

complete

Returns Boolean value that indicates whether or not the browser is finished loading the image

height

Sets or returns the value of the height attribute of the tag in pixels

hspace

Sets or returns the value of the hspace attribute of the tag in pixels

id

Sets or returns the id of the image (In IE 4 This property is read-only)

isMap

Sets or returns a Boolean value that specifies If the image is a server side image map

longDesc

Sets or returns URL for a long description of The image

lowsrc

Sets or returns a URL to low-resolution Version of the image (for clients with lowresolution

name

Sets or returns the value of the name attribute Of the tag

src

Sets or returns the URL of the image (This Property can be change at any time. However, ,the new image is scaled to fit the height and width attribute of the first image

useMap

Sets or returns a URL(often with a bookmark Extension-#name)to use as client_side image map

vspace

Sets or returns the value of the vspace attribute Of the in pixels

width

Sets or returns the value of the width attribute of The tag in pixels

Methods Syntax: object.method_name() Method blur() click() focus()

Description Removes focus from the image Simulates a mouse-click on the image Gives focus to the image

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Syntax: object.event_name=”someJavaScriptCode” Event onAbort onBlur onClick onError onFocus onLoad

Description Executes some code when download of an image Executes some code when focus Executes some code when On the image Executes some code when Executes some code when Focus Executes some code when

a user abort the the image loses an a user clicks an Error occurs the image gets the image load

Ex: function setSrc() { var x=document.images; x[0].src=”hackanm.gif”; }

Array Object The Array object is used to store a set of values in single variable name. Each value is an element of the array and has an associated index number. You create an instance of the Array object with the “new” keyword. The following example creates two arrays, both of three elements each: var family_names=new Array(3); var family_names=new Array(“Tove”, Jani”,”Stale”); You can refer to a particular element in the array by using the name of the array and the index number. The index number starts at 0. If you create an array with a single numeric, you can assign data each of the elements in the array like this: family_names[0]=”Tove”; family_names[1]=”Jani”; family_names[2]=”Stale”; And the data can be retrieved by using the index number of the particular array element you want, like this: mother=family_names[0]; Properties Syntax: object.property_name Property constructor length prototype Training & Development Division

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Methods Syntax: object.property_name() Method concat() join(delimiter) pop() push(“element1”,”element2”) reverse() shift() slice(begin[,end]) sort() splice(index,howmany[,e11,e12]) toSource() toString() unShift(“element1”,”element2”) valueOf()

Description Joins two or more arrays and returns a new array Puts all the elements of an array into a string separated by a specified delimiter(comma is default) Removes and returns the last element of an array Adds one or more elements to the end of an array and returns the new length Reverse the order of the elements in an array Removes and returns the first element of an array Create new array from a selected section of an existing array Sort the elements of an array Adds and /or removes elements of an array Returns a string that represent the source code of the array Returns a string that represent the specified array and its elements Adds once or more elements to the beginning of an array and returns the new length Returns the primitive value of an array

Example: var famname =new Array(3); famname[0] =”Jani”; famname[1] =”Tove”; famname[2] =”Hege”; document.write(famname.length +””); document.write(famname.join(“.”) +””); document.write(famname.reverse() + “”); document.write(famname.push(“Ola”,”Jon”) +””); document.write(famname.pop() + “”); document.write(famname.shift() + ””);

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Date Object The Data object is used to work with date and time of client browser. To create an instance of the Date object and assign it to variable called “d”, you have to do the following declaration: var d=new Date(); After creating an instance of the Date object, you can access all the methods of the date object from the “d” variable. To return the current day in a month (from 1-31) of a Date object, write the following: d.getDate(); The Date object can also have the following parameters: new Date(milliseconds) new Date(dateString) new Date (yr_num, mo_num, day_num [, hr_num, min_num, sec_num, ms_num]) • • • •

Milliseconds – the number of milliseconds since 01 January, 1970 00:00:00 dateString – the date in a format that recognized by the Date.parse method yr_num, mo_num, day_num, -the year, month or day of the date hr_num, min_num, sec_num,ms_num- the hours, minutes, seconds and milliseconds

If you only use Date(), JavaScript creates an object for today’s date according to the time on the local machine. Here are some examples on how to create Date object: var d=new Date(“October 12, 1988 13:14:00”) var d=new Date (“October 12, 1988”) var d=new Date(88, 09,12,13,14,00) var d=new Deat(88, 09,12) var d=new Date(500)

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Properties Syntax: object.property_name Property constructor prototype

Description Contain the function that created an object’s prototype Allows addition of properties to a date

Methods Syntax: object.method_name() Method Date() getDate() getDay() getMonth() getFullYear() getYear() getHours() getMinutes() getSeconds() getMilliseconds() getTime() getTimezoneOffset() getUTCDate() getUTCDay() getUTCMonth() getUTCFullYear() getUTCHours() getUTCMinutes() getUTCSeconds() getUTCMilliseconds() parse() setDate() setFullYear() setHours() setMilliseconds() Training & Development Division

Description Returns a Date object Returns the date of a Date object (from 1-31) Returns the day of a Date object (from 0.6. 0=Sunday, 1=Monday, etc.) Returns the month of a Date object (from 011. 0=January,1=February, etc.) Returns the years of Date object(four digits) Returns the year of a Date object (from 0-99). Use getFullYear instead!! Returns the hour of a Date object (from 0-23) Returns the minute of a Date object (from 059) Returns the minute of a Date object (from 059) Returns the milliseconds of a Date object(from 0-999) Returns the number of milliseconds since midnight 1st Jan. 1970 Returns the time difference between the user’s computer and GMT Returns the date of Date object in universal(UTC)time Returns the date of Date object in universal time Returns the date of Date object in universal time Returns the four-digit year of a Date object in universal time Returns the hours of Date object in universal time Returns the minutes of a Date object in universal time Returns the seconds of a Date object in universal time Returns the milliseconds of a Date object in universal time Return a string date value that holds the number of milliseconds since January 01 170 00:00:00 Sets the date of the month in the Date object(from 1-31) Sets the year in the Date object(four digit) Sets the hours in the Date object(from 0-23) Sets the milliseconds in the Date object(from Page 277 of 282

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setMinutes() setMonth() setSeconds() setTime() setYear() setUTCDate() setUTCDay() setUTCMonth() setUTCFullYear() setUTCHours() setUTCMinutes() setUTCSeconds() setUTCMilliseconds() toGMTString() toLocaleString() toString()

0-999) Set the minute in the Date object (from 0-59) Sets the month in the Date object (from 0-11. 0=January, 1=February) Sets the seconds in the Date object(from 0-59) Sets the milliseconds after1/1-1970 Sets year in the Date object (00-99) Sets the date in the Date object, in universal time (from 1-31) Sets the day in the Date object, in universal time (from 0-6. Sundy=0, Monday=1, etc.) Sets the month in the Date object,in universal time (from 0-11. 0=January, 1=February) Sets the year in the Date object, in universal time(four digits) Sets the hour in the Date object, in universal time(from 0-23) Sets minutes in the Date object, in universal time(from 0-59) Sets the seconds in the Date object, in universal time(from 0-59) Sets the milliseconds in the date object, in universal time (from 0-999) Converts the Date object to a string, set to GMT time zone Converts the Date object to a string, set to the current time zone Converts the Date object to a string

Example: var timer=null; function stop() { clearTimeout(timer); } function start() { var time = new Date(); var hours = time.getHours(); var minutes =time.getMinutes(); minutes=((minutes< 10)? “0” :””) + minutes; var seconds =time.getSeconds(); seconds=((seconds< 10) ? “0” : “”) + seconds; var clock =hours + ”:” + minutes + “:” + seconds; document.forms[0].display.value = clock; timer = setTimeout(“start()”,1000); } Training & Development Division

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Math Object The built-in Math object includes mathematical constants and functions. You do not need to create the Math object before using it. To store a random number between 0 and 1 in a variable called “r_number”: r_number=Math.random(); To store the rounded number of 8.6 in a variable “r_number”: r_number=Math.round(8.6) Properties Syntax: object.property_name Property E LN2 LN10 LOG2E LOG10E PI SQRT1_2 SQRT2

Description Returns the base of a natural logarithm Returns the natural logarithm of 2 Returns the natural logarithm of 10 Returns the base-2 logarithm of E Returns the base-10 logarithm of E Returns PI Returns 1 divided by the square root of 2 Returns the square root of 2

Methods Syntax: object.method_name() Method abs(x) acos(x) asin(x) atan(x) atan2(y,x) ceil(x) cos(x0 exp(x) floor(x) log(x) max(x,y) min(x,y) pow(x,y) random() round(x) sin(x) sqrt(x) tan(x)

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Description Returns the absolute value of x Returns the arccosine of x Return the arcsine of x Return the arctangent of x Return the angle from the x axis to a point Return the nearest integer greater than or equal to x Returns the cosine of x Returns the value of E raised to the power of x Returns the nearest integer less than or equal to x Returns the natural log of x Returns the number with the highest value of x and y Returns the number with the lowest value of x and y Return the value of the number x raised to the power of y Returns a random number between 0and 1 Round x to the nearest integer Returns the sine of x Returns the square root of x Returns the tangent of x

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Example: document.write(Math.max(2,4)) Output: 4

String object The String object is used to work with text/Strings. The String object’s properties and method are described below: Properties Syntax: object.property_name Property constructor length

Description Returns the number of characters in a string

Methods Syntax: object.method_name() Method anchor(“anchorname”) big() blink() bold() charAt(index) charCodeat() concat() fixed() fontColor() fontSize() fromCharcode() indexOf() italics() lastindexOf()

link() match() replace() search()

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Description Returns a string as an anchor Returns a string in big text Returns a string blinking Returns a string in bold Returns the character at a specified position Returns the Unicode of the character at a specified position Returns two concatenated string Returns a string as teletype Returns a string specified color Returns a string specified size Returns the character value of a Unicode Returns the position of the first occurrence of a specified string inside another string. Returns -1 if it never occurs Returns a string in italic Returns the position of the first occurrence of specified string inside another string. Returns -1 if it never occurs. Note: This method starts from the right and moves left! Returns a string as a hyperlink Similer to indexOf and lastIndexOf, but this method returns the specified string, or “null”, instead of a numeric value Replaces some specified characters with some new specified characters Returns an integer if the string contain some specified characters, if not it returns -1 Page 280 of 282

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slice() small() splite() strike() sub() substr() substring() sup() toLowerCase() toUpperCase()

Returns a string containing a specified character index Returns a string as a small text Splits a string into an array of strings Returns a string strikethrough Returns a string as subscript Returns the specified characters. 14,7 returns 7 character, from the 14th character (starts at 0) Returns the specified character. 7,14 returns all character from the 7 th up to 13 but not including the 14th (starts at 0) Returns a string as superscript Converts a string to lower case Converts a string to upper case

Example of String Object with Methods Strings Demo var strn="Welcome to L&T Infotech"; document.write("strn = " + strn); document.write(""); document.write("strn.indexOf('&') = " + strn.indexOf('&')); //Index starts from 0th position document.write(""); document.write("strn.charAt(5) = " + strn.charAt(5)); document.write(""); document.write("strn.substr(2,3) = " + strn.substr(2,3)); document.write(""); document.write("strn.substring(2,3) = " + strn.substring(2,3));

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Output:

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