AS3 to JS compilers

Haxe

From the intro page:

Haxe (pronounced as hex) is an open source programming language.

While most other languages are bound to their own platform (Java to the JVM, C# to .Net, ActionScript to the Flash Player), Haxe is a multiplatform language.

It means that you can use Haxe to target the following platforms :

Javascript : You can compile a Haxe program to a single .js file. You can access the typed browser DOM APIs with autocompletion support, and all the dependencies are resolved at compilation time.

Flash : You can compile a Haxe program to a .swf file. Haxe can compile for Flash Players 6 to 10, with either "old" Flash<8 API or newest AS3/Flash9+ API. Haxe offers very good performance and language features to develop Flash content.

NekoVM : You can compile a Haxe program to NekoVM bytecode. This can be used for server-side programming such as dynamic webpages (using mod_neko for Apache) and also for commandline or desktop applications, since the NekoVM can be embedded and extended with some other DLL.

PHP : You can compile a Haxe program to .php files. This enable you to use a high level strictly-typed language such as Haxe while keeping full compatibility with your existing server platform and libraries.

C++ : You can now generate C++ code from your Haxe source code, with the required Makefiles. This is very useful for creating native applications, for instance in iPhone development.

Also of possible interest to you: Haxer, a java project i wrote that helps convert AS3 code to Haxe code. It is not complete, but it gives you a good start in converting your code.