CoffeeScript - JavaScript done right

CoffeeScript main site


Book: CoffeeScript: Accelerated JavaScript Development @ PragProg

Video: CoffeeScript Basics Video @ railscasts.com

Podcast: Trevor Burnham on CoffeeScript @ Herding Code

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.

# Assignment:
number   = 42
opposite = true

# Conditions:
number = -42 if opposite

# Functions:
square = (x) -> x * x

# Arrays:
list = [1, 2, 3, 4, 5]

# Objects:
math =
root:   Math.sqrt
square: square
cube:   (x) -> x * square x

# Splats:
race = (winner, runners...) ->
print winner, runners

# Existence:
alert "I knew it!" if elvis?

# Array comprehensions:
cubes = (math.cube num for num in list)