The documentation for Flash CS4 Professional includes a tremendously useful table titled “ActionScript 2.0 Migration.” An introductory caption humbly states, “The following table describes the differences between ActionScript 2.0 and 3.0,” which leads to a catalog so lengthy, it would fill over 50 pages if reproduced in this book. To locate this document, look in the appendixes of the ActionScript 3.0 Language and Components Reference or search the term “migration” in the Help panel. This document is also available on the Adobe online Help Resource Center:
This chapter will help you find your bearings from a migration standpoint, and navigate among these changes.
As programming languages evolve, existing workflows may change, new features are usually added, and older features are sometimes removed. This is as true for ActionScript as it is for Java, C#, Python, PHP, and countless others. In the company of programmers at large, you’re not alone. The changes in ActionScript 3.0 may seem startlingly plentiful, but historically speaking, Flash has been through this sort of remodeling before. Developers encountered a similar paradigm shift when Macromedia Flash 5 introduced the language that, for clarity, was later renamed ActionScript 1.0. The original naming scheme didn’t include version numbering, and was therefore referred to simply as “ActionScript.” ...