Editing ActionScript (section)

====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, [[Adobe Flash 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 of programming languages|syntax]], such as the keywords {{Mono|class}} and {{Mono|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 programming|class-based]] inheritance syntax was a layer on top of the existing prototype-based system. With ActionScript 2.0, developers could constrain [[variable (programming)|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 (programming language)|Java]] and [[C++]]. This version conformed partially to the [[ECMAScript]] Fourth Edition draft specification.