So the first thing you may have noticed is that everything in AS2 that had an underscore in front of it no longer does in AS3. That is a MAJOR issues for all of us lazy coders that just want to copy and paste old AS 2 code into an AS3 document – it will fire all sorts of errors such as this one:
Warning: 1058: Migration issue: The property _x is no longer supported. Use the DisplayObject.x property instead.
So lets say you have a FLA with a MovieClip on the Stage with an instance name of tester_mc and you want to set its x position to 89.
tester_mc._x = 89;
tester_mc.x = 89;
Another little tidbit to keep in mind is that all values that ran from 1 to 100 such as the alpha setting are now running from 0 to 1. If we use the same MovieClip from the last example and set it’s opacity to 50% here is the syntax (remembering to drop the underscore!).
tester_mc._alpha = 50;
tester_mc.alpha = 0.5
These are very simple changes but they have a major impact if you miss one – your program will not run and eventually you will go crazy and want to fight the elderly.
Since we’re on the topic of errors, I have been working to document all of my encounters with both compiler and runtime errors in Flash.