Alpha

Summary

Though Flash Player 6 is the earliest version to support ActionScript 2.0, authoring tools couldn't compile ActionScript 2.0 until the release of Flash Player 7.

Variable scoping more consistent with JavaScript

Flash 6 changed the way variables are resolved within function scopes. In Flash Player 5 content, the following example would allow this function to change the _x property of any movie clip that used it.

MovieClip.prototype.moveBy = function(distance){
	_x += distance;
}

In Flash Player 6 content, however, the _x would reference whatever timeline instance the prototype was defined in (most likely _root). For this to work in Flash Player 6, the property must be prefixed by the this keyword.

MovieClip.prototype.moveBy = function(distance){
	this._x += distance;
}

This allows the variable to be properly resolved as the variable of the calling movie clip instance rather than the variable inherited by the containing scope.