The Little Book on CoffeeScript - Syntax

CoffeeScript Syntax Firstly, before we get any further into this section, I want to reiterate that while CoffeeScript's syntax is often identical with JavaScript's, it's not a superset, and therefore some JavaScript keywords, such as function and var aren't permitted, and will throw syntax errors. If you're writing a CoffeeScript file, it needs to be pure CoffeeScript; you can't intermingle the tw