From forum post: http://www.sublimetext.com/forum/viewtopic.php?f=4&t=3718

Here's the documentation if you want to give it a shot yourself.

http://sublimetext.info/docs/en/extensibility/syntaxdefs.html

That's not really "compiling", it's merely linting. There's a good package called SublimeLinter which will do as-you-type linting for a range of different languages, including Javascript (using JSHint) https://github.com/Kronuz/SublimeLinter

how do you mean "compile"?

This function also exists in Komodo, where it is called "Smart Caps". Works great, and I'm missing it in ST!