ActionScript for Flash MX: The Definitive Guide, Second Edition

_global Object

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ActionScript Language Reference

_global Object

container for global variables

Flash 6

_global.variableName

Description

The _global object enables the creation of global variables (i.e., variables that are available

from the timeline of any movie clip or level). Unlike in JavaScript, in ActionScript there is

no “global execution context” where variable definitions automatically create global vari-

ables. All nonlocal variables created in ActionScript are scoped to the movie clip in which

they are created. To make a variable directly accessible throughout all timelines in a movie,

we must deliberately add a property to

_global. For example:

// Add a property, age, to _global. Creates a global variable, age.

_global.age = 31;

// Access age from any timeline:

trace(age); // Displays: 31

Using global variables, we can make a function, property, or object available globally, much

like the built-in classes and objects (Math, TextField, Mouse, etc.). For example, if we want

to make the CountDown class a global class, we can use the following code (see Function.

apply( ) for the full listing for CountDown):

_global.CountDown = function (obj, meth, delay) {

// ... Class code here

};

Then, from any timeline, we can create instances of CountDown directly, as in:

theTimer = new CountDown(game, ...