With JSCocoa, you can write Cocoa applications (almost) entirely in Javascript or use it as a Plugin engine (like Acorn and Spice). JSCocoa uses WebKit's Javascript framework, JavascriptCore. JSCocoa is a way to use Cocoa from Javascript. It works on the Mac (i386, x86_64, PPC), the iPhone and the iPhone simulator. You can write new Cocoa classes in Javascript, replace existing methods of classes