Introduction to Flex 2

ActionScript 3.0

The common language of Flex 2 applications is ActionScript 3.0. You can't use any older versions of ActionScript, nor is it possible to create a functional application without at least some ActionScript 3.0. Additionally, we will soon see that MXML and AS3 are fundamentally related.

ActionScript's third incarnation is a mature language, as well as being substantially different from ActionScript 2. This chapter will rapidly cover all the fundamental aspects of ActionScript 3.0, but is by no means a full course. For more instruction, there is a list of useful further reading at the bottom of this Short Cut.

Where Are You Coming From?

Readers who understand ActionScript 2 should be comfortable transitioning to ActionScript 3.0. The following chapter specifically addresses new concepts since AS2, so read on!

Readers versed in C# or Java should find themselves at home with AS3 in short time, but should note a few differences in syntax and features. In any case, this chapter assumes, at minimum, basic knowledge of object-oriented programming.

Main Features

ActionScript is an ECMAScript language; ActionScript 3.0 implements the draft of ECMAScript (ECMA-262) Edition 4. This means two things: one, its true name is ridiculous and you don't have to remember it, and two, it is a draft, so there may be incremental changes in the future. Ecma International is an international standards organization that oversees ECMAScript and other technological standards. JavaScript is another implementation ...