EnterFrame handler to run only while timeline is stopped on a certain frame - actionscript-3

Question

I have some code in a frame. It's basically
this.addEventListener(Event.ENTER_FRAME, handleUpdate);
function handleUpdate(e:Event):void
{...}
I want the code to be executed only when on that frame. But the handleUpdate function keeps getting called even when I'm out of that frame.
The timeline is stopped on this frame, and I want the handleUpdate to run continuously until the timeline moves off the frame.

Answer 1

If you're set on having the code for this on the frame in question, then you could do this:
var tmpCurFrame:int = currentFrame; //store the current frame
this.addEventListener(Event.ENTER_FRAME, handleUpdate)
function handleUpdate(e:Event):void {
if (tmpCurFrame != currentFrame) { //if the frame has changed, stop the frame handler
this.removeEventListener(Event.ENTER_FRAME, handleUpdate);
return;
}
//do your code
}
handleUpdate(null);
As an aside, it's much cleaner to have a document class and other class files that manage this sort of thing instead of using frame scripts. But if you all you're looking for is a quick and dirty tweak to your existing code, this should do the trick.

Answer 2

Haven't you heard about addFrameScript ?
It's perfect for your needs.
var desiredFrame = 25; // Timeline frame (starts from 1)
this.addFrameScript(desiredFrame-1, onFrame25); // 1st param is zero-based
function onFrame25():void
{
trace("I'm on frame", desiredFrame);
}

Answer 3

There's a few things you should consider with your approach:
Adding an ENTER_FRAME listener on the frame you care about happens after you enter that frame, so if the movieclip is playing you won't get an ENTER_FRAME event until the next frame (at which time it may have moved off that frame).
Be aware that code on a frame executes every time the playhead enters that frame, and you should be careful to remove listeners when appropriate for memory leak purposes.
So one approach would be to place this code on the frame in question - note that it also nicely removes its listener:
var thisFrame:int = currentFrame;
function handleUpdate(e:Event) {
if (currentFrame==thisFrame) {
// your code here...
} else {
// remove listener if we moved off the frame
removeEventListener(Event.ENTER_FRAME, handleUpdate);
}
}
// call it now because the listener won't fire until next frame
handleUpdate(null);
// add listener in prep for next ENTER_FRAME, though note that
// if we move off this frame, then the listener is removed above
addEventListener(Event.ENTER_FRAME, handleUpdate);
Another approach would be adding the following code on frame 1, so the listener always runs and is never cleaned up, and only performs the code when on frame 12:
addEventListener(Event.ENTER_FRAME, handleUpdate);
function handleUpdate(e:Event):void
{
if (currentFrame==12) {
// your code here...
}
}