2003–2006: ActionScript 2.0 The next major revision of the language, ActionScript 2.0, was introduced in September 2003 with the release of Flash MX 2004 and its corresponding player, Flash Player 7. In response to user demand for a language better equipped for larger and more complex applications, ActionScript 2.0 featured compile-time type checking and class-based syntax, such as the keywords class and extends. (While this allowed for a more structured object-oriented programming approach, the code would still be compiled to ActionScript 1.0 bytecode, allowing it to be used on the preceding Flash Player 6 as well. In other words, the class-based inheritance syntax was a layer on top of the existing prototype-based system.) With ActionScript 2.0, developers could constrain variables to a specific type by adding a type annotation so that type mismatch errors could be found at compile-time. ActionScript 2.0 also introduced class-based inheritance syntax so that developers could create classes and interfaces, much as they would in class-based languages such as Java and C++. This version conformed partially to the ECMAScript Fourth Edition draft specification.
2006–today: ActionScript 3.0 In June 2006, ActionScript 3.0 debuted with Adobe Flex 2.0 and its corresponding player, Flash Player 9. ActionScript 3.0 was a fundamental restructuring of the language, so much so that it uses an entirely different virtual machine. Flash Player 9 contains two virtual machines, AVM1 for code written in ActionScript 1.0 and 2.0, and AVM2 for content written in ActionScript 3.0. Actionscript 3.0 added limited support for hardware acceleration (DirectX, OpenGL).
The update to the language introduced several new features:
- Compile-time and run-time type checking—type information exists at both compile-time and runtime.
- Improved performance from a class-based inheritance system separate from the prototype-based inheritance system.
- Support for packages, namespaces, and regular expressions.
- Compiles to an entirely new type of bytecode, incompatible with ActionScript 1.0 and 2.0 bytecode.
- Revised Flash Player API, organized into packages.
- Unified event handling system based on the DOM event handling standard.
- Integration of ECMAScript for XML (E4X) for purposes of XML processing.
- Direct access to the Flash runtime display list for complete control of what gets displayed at runtime.
- Completely conforming implementation of the ECMAScript fourth edition draft specification.
- Limited support for dynamic 3D objects. (X, Y, Z rotation, and texture mapping)