JavaScript Pocket Reference

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JavaScript Pocket Reference

guage a script is written in is with the type attribute. For Java-

Script, set this attribute to the MIME type “text/javascript”:

<script src="functions.js"

language="JavaScript1.5"

type="text/javascript"></script>

Event handlers

JavaScript code may also appear as the value of an event han-

dler attribute of an HTML tag. Event handler attribute

names always begin with “on”. The code specified by one of

these attributes is executed when the named event occurs.

For example, the following HTML creates a button, and the

onclick attribute specifies an event handler that displays an

alert (a dialog box) when the user clicks the button:

<input type="button" value="Press Me"

onclick="alert('Hello World!');">

A list of other available event handler attributes is included

later in this section.

JavaScript URLs

JavaScript code may appear in a URL that uses the special

javascript: pseudo-protocol. The content of such a URL is

determined by evaluating the JavaScript code and converting

the resulting value to a string. If you want to use a JavaScript

URL to execute JavaScript code without returning any docu-

ment content that would overwrite the current document,

use the

void operator:

<form action="javascript:void validate()">

The Window Object

The Window object represents a web browser window. In

client-side JavaScript, the Window object is the global object

that defines all top-level ...