Functions

Reusable blocks of logic. The site's namesake — the function declaration.

Function declaration

Hoisted, so it can be called before it appears in the source.

function greet(name) {
  return "Hello, " + name + "!";
}

greet("world"); // "Hello, world!"

Function expression

const square = function (n) {
  return n * n;
};

Arrow function

const double = (n) => n * 2;
const add = (a, b) => a + b;