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.

240

|

Chapter 10: Events and Event Handling

Suppose, for example, we have a movie clip on stage named square, which has an

onClipEvent(load) handler defined:

onClipEvent (load) {

trace("movie loaded");

}

What happens when we duplicate square to create square2?

square.duplicateMovieClip("square2", 0);

Answer: Because the onClipEvent(load) handler is copied to square2 when we dupli-

cate square, the birth of square2 causes its load handler to execute, which displays

“movie loaded” in the Output window. By using this automatic retention of han-

dlers, we can create slick recursive functions with very powerful results. For a dem-

onstration, refer to MovieClip.onLoad( ) in the Language Reference.

In contrast, suppose we have a movie clip named

circle and we assign it an

onEnterFrame( ) event handler property as follows:

circle.onEnterFrame = function ( ) {

trace(this._name);

}

What happens when we duplicate circle to create circle2?

circle.duplicateMovieClip("circle2", 1);

Answer: Only circle’s name appears in the Output window. The onEnterFrame( )

event handler property is not copied to

circle2,socircle2’s name does not appear

in the Output window. To force every duplicate of the

circle clip to define an

onEnterFrame( ) event handler property, we can set the property on a frame of

circle’s timeline: ...