JavaScript Pocket Reference

Client-side JavaScript

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explaining how JavaScript code is embedded in HTML files,

then goes on to introduce the client-side JavaScript objects,

JavaScript events and event handling, and JavaScript secu-

rity restrictions.

JavaScript in HTML

JavaScript code may be embedded in HTML files in the form

of scripts, event handlers and URLs, as detailed below.

The <script> tag

Most JavaScript code appears in HTML files between a

<script> tag and a </script> tag. For example:

<script>

document.write("The time is: " + new Date());

</script>

In JavaScript 1.1 and later you can use the src attribute of

the

<script> tag to specify the URL of an external script to be

loaded and executed. Files of JavaScript code typically have a

.js extension. Note that the

</script> tag is still required

when this attribute is used:

<script src="library.js"></script>

HTML allows scripts to be written in languages other than

JavaScript, and some browsers, such as Internet Explorer,

support languages such as VBScript. You can use the

language attribute to specify what language a script is writ-

ten in. This attribute defaults to “

JavaScript” in all brows-

ers, so you do not usually have to set it. You can also use

attribute values such as “JavaScript1.3” and “JavaScript1.5”

to specify the version of JavaScript your code uses. Browsers

that do not support the specified version of the language sim-

ply ignore the script.

HTML 4 does not