AS 发展小计

2000 -- 2003: ActionScript 1.0, 和 Flash 5.0 一起发布；变成可文本编辑（以前是从对话框和下拉菜单中选择，当然，那个时候不叫 AS）添加 switch 语句和 strict equality 操作；
2003 -- 2006: ActionScript 2.0 和 Flash MX 2004 and Flash Player 7 一起发布；Therefore, ActionScript 2.0 featured compile-time type checking and class-based syntax, using the keywords class and extends, for example.
2006 -- today ActionScript 3.0 首次和 Adobe Flex 2.0 and Flash Player 9 发布。加入的新特性使它变得更加强大：

• Compile-time and runtime type checking—type information exists at both compile-time and runtime
• Improved performance from a class-based inheritance system that was separate from the prototype-based inheritance system
• Support for packages, namespaces, and regular expressions
• Compilation to an entirely new type of bytecode, incompatible with ActionScript 1.0 and 2.0 bytecode
• A revised Flash Player organized into packages
• Unified event handling system that is based on the DOM event handling standard
• Integration of ECMAScript for XML (E4X) for the purpose of XML processing
• Direct access to the Flash runtime display list for complete control of what gets displayed at runtime
• A completely conforming implementation of the ECMAScript Fourth Edition Draft specification
• Backward compatibility