| MovieClip.onUnload( ) Event Handler | Flash 6 |
| callback invoked when the clip is removed from the Stage or when unloadMovie( ) executesFlash 5; callback form introduced in |
The onUnload( ) event handler is the callback form (and more modern analogue) of the legacy onClipEvent (unload) event handler. The onUnload( ) event is the opposite of the onLoad( ) event; it occurs when mc expires�that is, it occurs immediately after the last frame in which mc is present on stage (but before the first frame in which it is absent). The onUnload( ) event does not apply to main movies (e.g., _root, _level1, etc.)
The following incidents trigger onUnload( ):
The playhead reaches the end of the span of frames upon which mc resides.
mc is removed via the removeMovieClip( ) function (which deletes clips generated by the attachMovie( ) and duplicateMovieClip( ) functions).
The unloadMovie( ) function is invoked on mc.
mc has an external .swf file loaded into it.
This last onUnload( ) event trigger may seem a little odd, but it is actually a natural result of the way movies are loaded into Flash. Anytime a .swf or .jpg file is loaded into a movie clip, the previous contents of that clip are displaced, triggering an onUnload( ) event. Here's an example that illustrates the behavior of the onLoad( ) and onUnload( ) events in connection with loadMovie( ):
In the Flash authoring tool, we place an empty movie clip on stage at frame 1 of a movie's main timeline. We name our clip emptyClip.
At frame 5 of the main timeline, we load the movie test.swf into emptyClip using the following code:
emptyClip.loadMovie("test.swf");We play the movie using Control 
Play movie.
The results are:
The emptyClip clip appears on frame 1, causing an onLoad( ) event.
On frame 5, the loadMovie( ) function is executed in two stages:
The onUnload( ) event typically is used to perform housecleaning code�code that cleans up the Stage or resets the program environment in some way. An onUnload( ) handler also provides a means for performing some action (such as playing another movie) after a movie clip ends.
Unlike its cousin onLoad( ), whose callback form has limited use, onUnload( ) works identically whether defined as a callback or in an onClipEvent(unLoad) block. However, the usual differences between callback handlers and onClipEvent( ) handlers still apply:
When the contents of mc are unloaded, the onUnload( ) callback is lost, but the onClipEvent(unload) handler is retained.
When mc is duplicated via duplicateMovieClip( ), the onUnload( ) callback is not copied to the duplicate clip, but the onClipEvent(unLoad) handler is.
Perhaps surprisingly, in Flash 6, onUnload( ) is not triggered when the Flash Player is closed or when _level0 (the main movie) is removed from the Player. Macromedia may address this idiosyncrasy in the future.
MovieClip.onLoad( ), MovieClip.unloadMovie( )
