ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Other Operators

|

139

Array-Element/Object-Property Operator

As we’ll see in Chapters 11 and 12, we use the [] operator to retrieve and set the

value of an array element or an object property. When accessing an array, it takes the

form:

array[element]

where array is the name of an array or an array literal and element is an expression

that resolves to a zero-relative, nonnegative integer representing the index of the

array element to access.

When accessing an object, the

[] operator takes the form:

object[property]

where object is an object name or object literal and property is any expression that

resolves to a string representing the name of the object property to access.

When used on the left side of an assignment operator (

=), the element or property is

assigned the new value shown on the right side of the expression:

var colors = new Array(); // Create a new array

colors[0] = "orange"; // Set its first element

colors[1] = "green"; // Set its second element

var ball = new Object(); // Create a new object

var myProp = "xVelocity"; // Store a string in a variable

ball["radius"] = 150; // Set the radius property

ball[myProp] = 10; // Set the xVelocity property through myProp

When used anywhere else, the expression returns the value of the specified element

or property:

diameter = ball["radius"] ...