AJAX - The Complete Reference

562 Part IV: Appendixes

Commonly it is used to shortcut object reference paths. For example, in this markup

fragment you might use document.getElementById("field1") in the onblur handler,

but this is much more concise:

<input type="text" value="Test" id="field1" onblur="alert(this.value)" />

When used in the global context, this refers to the current Window.

ECMAScript Built-In Objects

Table A-8 lists the built-in objects found in ECMAScript-based languages such as JavaScript.

These objects are part of the language itself, as opposed to host (or browser) objects that are

provided by the browsers. Note that you cannot instantiate Global or Math objects. The

Global object is not even explicitly addressable. It is defined as the outermost enclosing

scope (so its properties are always addressable).

NNOT EOTE Some other objects encountered in JavaScript like Document are part of the W3C DOM

specification. While others like Navigator are not part of any current specification but are an

ad hoc standard.

The Global object in particular contains a variety of useful utility properties and

methods. Aspiring JavaScript programmers should become very familiar with the features

of Global, summarized in Table A-9.

Object Description

Array Provides an ordered list data type and related functionality

Boolean Object corresponding to the primitive Boolean data type

Date Facilitates date- and time-related computation

Error Provides the ability to create a variety of exceptions (and includes a variety

of derived objects such as SyntaxError)

Function Provides function-related capabilities such as examination of function

arguments

Global Provides universally available functions for a variety of data conversion and

evaluation tasks

Math Provides more advanced mathematical features than those available with

standard JavaScript operators

Number Object corresponding to the primitive number data type

Object Generic object providing basic features (such as type-explicit type conversion

methods) from which all other objects are derived

RegExp Permits advanced string matching and manipulation

String Object corresponding to the primitive string data type

TABLE A-8 JavaScript Built-In Objects