stage access out of DocumentRoot in AS3

One of my first challenges in understanding AS3 was the idea that Stage and _root are no longer global (and this is a good thing).

DISCLAIMER: In general, accessing root is considered a crap coding practice - I like to call it CCP. :-D There are a few cases that using root may be helpful - but if you are questioning whether to use it or not - then the answer is probably, “NO!”

Essentially, Stage and _root can now be accessed as:

// accessing root is almost always a bad idea
_root = MC.root;
Stage = MC.stage;

If you try and access




anywhere else than your document root class - you will get this error:

Error 1120: Access of undefined property stage.
Error 1120: Access of undefined property root.

The biggest issue for me was stage. Before, I used to always access the Stage.height and Stage.width dimensions a lot in order to set properties of things that I created outside of the DocumentRoot.

If you want to access stage from anywhere else but the DocumentRoot class - you’ll need to do something like this:

var myMC:MovieClip = new MovieClip();
var _stage:Stage = myMC.stage;
trace(“the AS3 Stage.width: “+_stage.stageWidth);
trace(“returns the width of objects on stage: “+_stage.width);
trace(“the AS3 Stage.height: “+_stage.stageHeight)
trace(“returns the height of objects on stage: “+_stage. height);

Something cool to note is that


refers to the width of ALL objects in the stage - flash actually is treating it as its own object so you can differentiate between the width of what’s on the stage and the stage itself.

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