Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types,
and warns about common JavaScript pitfalls. It is used in many of
Google's JavaScript apps, including Gmail, Google Web Search, Google
Maps, and Google Docs. 

WWW:	http://code.google.com/closure/compiler/