ActionScript3完全符合ECMAScript第四版规范，这可以简化xml解析。
E4X 最主要的应用可能是把XML解析成易于*纵的ECMAScript对象。
E4X is probably used most often as a way to parse XML into ECMAScript objects that can be very easily manipulated.
The created ECMAScript object is responsible for all the things that cannot be done declaratively with the markup, so basically it ACTS as a controller.
创建的ECMAScript对象负责无法用标记声明完成的一切工作，因此基本上是作为一个控制器。
