This book has been updated to include JavaScript 1.2 features, with the exception of JavaScript properties and objects that support layers and style sheets. For information on these subjects, see Dynamic HTML in Netscape Communicator.

Preliminary, last modified: 11/26/97.

What's New in Navigator 4.0

What You Should Already Know

How to Use JavaScript Documentation

Document Conventions

Part 1 Using JavaScript in Navigator

This chapter introduces JavaScript, discusses some of the fundamental concepts of JavaScript in Navigator and provides basic examples. It shows JavaScript code in action, so you can begin writing your own scripts immediately, using the example code as a starting point.

What is JavaScript?

JavaScript in Navigator

JavaScript on the Server

JavaScript, the Core Language

JavaScript and Java

Embedding JavaScript in HTML

Using the SCRIPT Tag

Specifying a File of JavaScript Code

Using JavaScript Expressions as HTML Attribute Values

Using Quotation Marks

Specifying Alternate Content With the NOSCRIPT Tag

Defining and Calling Functions

Using the Write Method

Printing Output

Displaying Output

Validating Form Input

Example Validation Functions

Using the Validation Functions

Debugging JavaScript

JavaScript applications in the Navigator are largely event-driven. Events are actions that occur usually as a result of something the user does. For example, clicking a button is an event, as is changing a text field or moving the mouse over a link. For your script to react to an event, you define event handlers, such as onChange and onClick.

Defining an Event Handler

Example: Using an Event Handler

Calling Event Handlers Explicitly

The Event Object

Event Capturing

This chapter describes JavaScript objects in Navigator and how to use them. These client-side JavaScript objects are sometimes referred to as Navigator objects, to distinguish them from server-side objects or user-defined objects.

Navigator Object Hierarchy

Document Properties: an Example

JavaScript Reflection and HTML Layout

Key Navigator Objects

window and Frame Objects

document Object

Form Object

location Object

history Object

navigator Object

Navigator's Object Arrays

JavaScript lets you create and manipulate windows and frames for presenting HTML content. The window object is the top-level object in the JavaScript client hierarchy; Frame objects are similar to window objects, but correspond to "sub-windows" created with the FRAME tag in a FRAMESET document.

Opening and Closing Windows

Opening a Window

Closing a Window

Using Frames

Creating a Frame

Updating a Frame

Referring To and Navigating Among Frames

Creating and Updating Frames: an Example

Referring to Windows and Frames

Referring to a Window's Properties, Methods, and Event Handlers

Referring to a Window in a Form Submit or Hypertext Link

Navigating among Windows and Frames

LiveConnect enables communication between JavaScript and Java applets in a page and between JavaScript and plug-ins loaded on a page. This chapter explains how to use LiveConnect in Netscape Navigator. It assumes you are familiar with Java programming.

Enabling LiveConnect

The Java Console

About the Netscape Packages

Using the Netscape Packages

JavaScript to Java Communication

Accessing Java Directly

Controlling Java Applets

Controlling Java Plug-ins

Data Type Conversion

Java to JavaScript Communication

Getting a Handle for the JavaScript Window

Accessing JavaScript Objects and Properties

Calling JavaScript Methods

Data Type Conversion

This chapter describes some special concepts and applications that extend the power and flexibility of Navigator JavaScript.

Using JavaScript URLs

Using Client-Side Image Maps

Using Server-Side Image Maps

Using the Status Bar

Creating Hints with onMouseOver and onMouseOut

Using Cookies

Limitations

Using Cookies with JavaScript

Using Cookies: an Example

Determining Installed Plug-ins

mimeTypes Array

plugins Array

This chapter describes the security models of the JavaScript language for Navigator 2.0 and later releases. This model was extended significantly between the Navigator 3.0 and Navigator 4.0 releases.

Same Origin Policy

New Access Errors

Origin Checks and Layers

Origin Checks and Java Applets

Using Data Tainting in Navigator 3.0

How Tainting Works

Enabling Tainting

Tainting and Untainting Individual Data Elements

Tainting that Results from Conditional Statements

Using Signed Scripts in Navigator 4.0

Introduction to Signed Scripts

Identifying Signed Scripts

Using Expanded Privileges

Writing the Script

Signing Scripts

Troubleshooting Signed Scripts

Part 2 The Core JavaScript Language

This chapter discusses values that JavaScript recognizes and describes the fundamental building blocks of JavaScript expressions: variables and literals.

Values

Data Type Conversion

Variables

Variable Scope

Literals

Integers

Floating-Point Literals

Boolean Literals

String Literals

This chapter describes JavaScript expressions and operators, including assignment, comparison, arithmetic, bitwise, logical, string, and special operators. It also describes regular expressions.

Expressions

Operators

Assignment Operators

Comparison Operators

Arithmetic Operators

Bitwise Operators

Logical Operators

String Operators

Special Operators

Operator Precedence

Regular Expressions

Creating a Regular Expression

Writing a Regular Expression Pattern

Working With Regular Expressions

Examples

This chapter describes how to use objects, properties, functions, and methods, and how to create your own objects.

Objects and Properties

Functions

Defining Functions

Using Functions

Using the arguments Array

Creating New Objects

Using Object Initializers

Using a Constructor Function

Indexing Object Properties

Defining Properties for an Object Type

Defining Methods

Using this for Object References

Object Deletion

Several objects are predefined in core JavaScript and can be used in either client-side or server-side scripts. These objects are in addition to objects defined for server-side JavaScript and Navigator objects introduced in Chapter 3, "Using Navigator Objects." A handful of predefined functions can also be used in both client and server scripts.

Objects

Array Object

Boolean Object

Date Object

Function Object

Math Object

Number Object

RegExp Object

String Object

Functions

eval Function

isNaN Function

parseInt and parseFloat Functions

Number and String Functions

escape and unescape Functions

taint and untaint Functions

JavaScript supports a compact set of statements that you can use to incorporate a great deal of interactivity in Web pages. This chapter provides an overview of these statements.

Conditional Statement

if...else Statement

switch Statement

Loop Statements

for Statement

do...while Statement

while Statement

labeled Statement

break Statement

continue Statement

Object Manipulation Statements and Operators

new Operator

this Keyword

for...in Statement

with Statement

Comments

Part 3 Appendixes

This appendix lists the reserved words in JavaScript.

The string literals in this appendix can be used to specify colors in the JavaScript alinkColor, bgColor, fgColor, linkColor, and vLinkColor properties and the fontcolor method.

A cookie is a small piece of information stored on the client machine in the cookies.txt file. This appendix discusses the implementation of cookies in the Navigator client; it is not a formal specification or standard.

LiveAudio is LiveConnect aware. This appendix describes how you use JavaScript to control embedded LiveAudio elements.

JavaScript Methods for Controlling LiveAudio

Using the LiveAudio LiveConnect Methods

This appendix tells you how you can use JavaScript to filter your incoming mail and news when you use Netscape Messenger.

Creating the filter and adding to your rules file

News filters

Message Object Reference

Mail Messages

News Messages

Debugging your filters

A more complex example

Last Updated: 11/26/97 09:25:20