"Just like JavaScript but nicer to type." was a decent pitch to make CoffeeScript sound safe. But it's become so much more. And you get past the simplicity of that pitch quickly if you use CoffeeScript earnestly.

Going through the Table of Contents on http://jashkenas.github.com/coffee-script/ I've picked out the features of CoffeeScript that make it a different beast than just a JavaScript without warts.

* Lexical Scoping and Variable Safety * Conditional Assignment * Splats * Comprehensions * Everything is an Expression (&implicit return) * The Existential Operator * Classes, Inheritance, and Super * Destructuring Assignment * Function binding * Chained Comparisons * Extended Regular Expressions

This is beyond a simple sweetener for your JavaScript code. Yes, you could write your JavaScript like you write your CoffeeScript, but you wouldn't.

Try this little jewel in Try CoffeeScript and you'll see what I mean:

[open, contents..., end] = "<impossible>".split "" alert contents.join ""