Lesson 4 — Functions

Functions

A function groups reusable code under a name. The modern arrow form, const double = (n) => n * 2, is short and everywhere in JavaScript.

Why it matters: functions are the core building block of every JS app — you will pass them around, reuse them and combine them constantly.

Tip: an arrow function with no braces returns its expression automatically; add braces and you must write return yourself.