CoffeeScript is a little language that compiles into JavaScript. Underneath all
of those embarrassing braces and semicolons, JavaScript has always had a
gorgeous object model at its heart. CoffeeScript is an attempt to expose the
good parts of JavaScript in a simple way.

The golden rule of CoffeeScript is: "It's just JavaScript". The code compiles
one-to-one into the equivalent JS, and there is no interpretation at runtime.
You can use any existing JavaScript library seamlessly (and vice-versa). The
compiled output is readable and pretty-printed, passes through JavaScript Lint
without warnings, will work in every JavaScript implementation, and tends to run
as fast or faster than the equivalent handwritten JavaScript.