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.

Function Scope

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For example, here we issue a statement that creates a variable, score:

var score = 10;

If this statement were attached to clipA, the interpreter would set the value of score

in clipA. If the statement were attached to clipB, the interpreter would set the value

of

score in clipB.

Statements in the body of a function operate in their own, separate scope, called a

local scope. A function’s local scope is private to the function, distinct from the scope

of the clip or object to which the function is attached. A new local scope for the func-

tion is created each time the function is invoked and destroyed when the function

finishes executing. When resolving variables referenced in the statements of the func-

tion body, the interpreter looks first in the function’s local scope.

Function parameters, for example, are defined in the local scope of a function—not

on the timeline that bears the function. Hence, parameters are accessible only to the

statements of a function’s body and only while the function is running. Statements

outside the function have no access to the function’s parameters.

A function’s local scope provides a place for temporary “local” variables used solely

within a function. This eliminates potential name conflicts between local function

variables and timeline ...