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.

198

|

Chapter 9: Functions

Local Variables

Variables assigned to a function’s local scope are called local variables. Local vari-

ables, including parameters, are accessible only to statements in the body of the func-

tion in which they are defined and exist only while that function runs. To create a

local variable (other than the parameters that automatically become local variables),

we use the var statement inside any function, like this:

function funcName () {

var temp = "just testing!"; // Declares the local variable temp

}

Local variables are useful for holding information temporarily. Here, for example, we

use the local variable

lastSpacePlusOne to hold an interim result. Like all local vari-

ables, it dies when the function ends:

function getLastWord (text) {

var lastSpacePlusOne = text.lastIndexOf(" ") + 1; // Local

var lastWord = text.subString(lastSpacePlusOne, text.length); // Local

return lastWord;

}

// Displays: "word"

trace(getLastWord("Tell me the last word"));

// Displays: undefined. lastSpacePlusOne is local and not

// available outside the getLastWord() function.

trace(lastSpacePlusOne);

When local variables expire at the end of a function, the memory associated with

them is marked for automatic deletion. By using local variables to store all tempo-

rary values, we can conserve ...