Moving an image with actionscript

Question

I'm trying to move an image from position Y:0 to Y:-100 using
actionscript when the .swf file loads, as this is smoother than
conventional tweening??

Answer 1

Well Sim-Enzo is almost correct. You will have some problems
though because it is not really complete.
When you want to do things over time (move, fade, scale,
etc.) with actionscript you have two main choices –
onEnterFrame and setInterval. For the example given by Sim-Enzo I
would rewrite it like this:
myImageClip.onEnterFrlame=function(){
if(this._y>-100){
this._y-=10;
}else{
delete this.onEnterFrame;
this._y=-100
Here are why I would make these changes.
First the onEnterFrame is poorly named and confuses a lot of
folks. So remember onEnterFrame means "do this next bit of code at
the frame rate of the movie – even if the timeline is stopped
or there is only one frame."
Next. Each movie clip instance can only have one onEnterFrame
handler defined for it. So it is a good idea to assign each one to
an appropriate clip to avoid problems. By attaching this one to the
clip you want to move, myImageClip, you will also be able to assign
other ones to other clips and do whatever they need to do.
Then inside the event handler, notice how I refer to the clip
by "this" since the onEnterFrame is scoped to the myImageClip.
Finally, and this is probably most important, I have added an
else to the conditional. This makes sure that once your clip has
move to where it is supposed to go that the onEnterFrame is
stopped. Otherwise the onEnterFrame would just keep going –
it wouldn't move the clip anymore, but it would be using up
processor time. One errant onEnterFrame like this wouldn't probably
bring down your swf, but if you didn't do it with many different
ones you would notice.
I also added a little bit there which put the clip exactly at
the place I wanted. There are times in Flash where rounding errors
or other issues can make for surprises. I think it is good practice
to set the value to the exact required value.