ActionScript: The Definitive Guide

Named Array Elements

Elements are usually numbered but can also be named. Using named elements we can emulate so-called associative arrays or hashes . Note that named array elements cannot be manipulated by the Array methods ( push( ), pop( ), etc., covered later) and are not considered part of the numbered element list. An array with one named element and two numbered elements will have a length of 2, not 3. To access all the named elements in an array, therefore, we must use a for-in loop (discussed in Chapter 8), which lists both named and numbered elements.

Creating and Referencing Named Array Elements

To add an element that can later be retrieved by name, we use the familiar square brackets, with a string instead of a number, on an existing array:

                  arrayName[elementName] = expression

where elementName is a string. For example:

var importantDates = new Array( );
importantDates["dadsBirthday"] = "June 1";
importantDates["mumsBirthday"] = "January 16";

We may also use the dot operator, as follows:

                  arrayName.elementName = expression

In this case, elementName must be an identifier, not a string. For example:

var importantDates = new Array( );
importantDates.dadsBirthday = "June 1";
importantDates.mumsBirthday = "January 16";

Assuming that we know an element’s identifier (for example, dadsBirthday in the importantDates array), we can access it in one of two ways:

var goShopping = importantDates["dadsBirthday"];
var goShopping = importantDates.dadsBirthday;

Just as is the case when assigning ...