The creator of CoffeeScript credits http://createyourproglang.com/ for the knowledge required to build the language.

If you are interested in building your own programming language you should check it out. It gives you the tools and background you need to build something fun like this.

This is a great 5-minute overview of the compiler, in broad strokes. If you're looking to work on a little to-JS language of your own, I hope it's helpful in getting started.

The video isn't up online quite yet, but at JSConf earlier this month, Brendan Eich and I talked (http://brendaneich.com/2011/05/my-jsconf-us-presentation/) about encouraging this sort of language experimentation. There are lots of other examples available at http://altjs.org. Google's Traceur compiler, which implements their vision of the in-progress ES.next standard is a particularly good touchstone: http://code.google.com/p/traceur-compiler/wiki/LanguageFeatu...