User Guide

15
1
CHAPTER 1
Introduction to
ActionScript 3.0
This chapter provides an overview of ActionScript 3.0, the newest and most revolutionary
version of ActionScript.
Contents
About ActionScript. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Advantages of ActionScript 3.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
What’s new in ActionScript 3.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Compatibility with previous versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
About ActionScript
ActionScript is the programming language for the Flash Player run-time environment. It
enables interactivity, data handling, and much more in Flash content and applications.
ActionScript is executed by the ActionScript Virtual Machine, which is part of Flash Player.
ActionScript code is typically compiled into bytecode format by a compiler, such as the one
built into the Flash authoring tool or Flex Builder, or that is available in the Flex SDK and the
Flex Data Services. The bytecode is embedded in SWF files, which are executed by the Flash
Player, the run-time environment.
ActionScript 3.0 offers a robust programming model that will be familiar to developers with a
basic knowledge of object-oriented programming. Some of the key features of ActionScript
3.0 include the following:
■ A new ActionScript Virtual Machine, called AVM2, that uses a new bytecode instruction
set and provides significant performance improvements
■ A more modern compiler code base that adheres much more closely to the ECMAScript
(ECMA 262) standard and that performs deeper optimizations than previous versions of
the compiler
■ An expanded and improved application programming interface (API), with low-level
control of objects and a true object-oriented model