CoffeeScript is a simple, clean, fast language which compiles to JavaScript, either at build time, with a caching framework plugin on the server, or at runtime in the browser.

The syntax looks like a cross between Python and Haskell and, generally speaking, is used similarly enough to Python that you’ll have little trouble picking it up and using it comfortably.

It does have a few of what non-Ruby programmers will consider distasteful warts, but for the most part, it’s an elegant and delightful language.