CoffeeScript in Action

Chapter 3. First-class functions

This chapter covers

• Functions for representing computation
• Functions for events and event-driven I/O
• An introduction to higher-order functions
• Variable scope and closures

If you asked a dozen JavaScript programmers what they thought JavaScript got wrong, you’d probably get a dozen different answers. If you asked those same dozen people what JavaScript got right, they’d probably all answer, “First-class functions.” What does it mean that JavaScript has first-class functions, why does it matter, and how does CoffeeScript make functions even better? All will be answered in good time. First, though, what exactly is a function?

A function defines a transformation of input values called parameters to an output ...