ActionScript for Flash MX: The Definitive Guide, Second Edition

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

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Chapter 11: Arrays

To determine whether an object is an array, use the instanceof operator. For example:

var colors = ["red", "blue", "green"];

trace(colors instanceof Array); // Displays: true

Multidimensional Arrays

So far, we’ve limited our discussion to one-dimensional arrays, which are akin to a

single row or a single column in a spreadsheet. But what if we want to create the

equivalent of a spreadsheet with both rows and columns? We need a second dimen-

sion. ActionScript natively supports only one-dimensional arrays, but we can simu-

late a multidimensional array by creating arrays within arrays. That is, we can create

an array that contains elements that are themselves arrays (sometimes called nested

arrays).

The simplest type of multidimensional array is a two-dimensional array, in which

elements are organized conceptually into a grid of rows and columns—the rows are

the first dimension of the array, and the columns are the second.

Using a practical example, let’s consider how a two-dimensional array works. Sup-

pose we’re processing an order that contains three products, each with a quantity

and a price. We want to simulate a spreadsheet with three rows (one for each prod-

uct) and two columns (one for the quantity and one for the price). We create a sepa-

rate array for