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 8: Loop Statements

The onEnterFrame( ) loop frees us from nesting our code inside a movie clip and

doesn’t require a two-frame loop, as timeline loops do. All the action of a clip event

loop happens in a single event handler. To stop an onEnterFrame( ) loop, simply

remove the movie clip that bears it. For example:

processMoveBall_mc.removeMovieClip( );

Or, delete the onEnterFrame( ) handler:

delete processMoveBall_mc.onEnterFrame;

If our application is simple, we may wish to forego our empty clip onEnterFrame( )

loop altogether. In some cases, we can, quite legitimately, attach an event loop

directly to the clip being manipulated. In our

ball_mc example, we can avoid the

need for a separate empty clip by defining our onEnterFrame( ) handler directly on

the

ball_mc instance:

ball_mc.onEnterFrame = function ( ) {

this._x += 10;

}

We can even define the onEnterFrame( ) event loop on the main timeline by placing

this code on one of its frames:

this.onEnterFrame = function ( ) {

this.ball_mc._x += 10;

}

Notice that we intentionally avoid referring to the main timeline as _root, which may

change meaning if the entire movie is loaded into a movie clip.

In Flash Player 6, each movie clip (including the main timeline) can take only one

onEnterFrame( ) event handler. In most applications, ...