Lesson 20 — Generators

Functions that pause

A generator is written function* and can yield values one at a time. Calling it gives an iterator; each .next() runs the function until the next yield and returns { value, done }. Because it pauses, an endless while (true) loop is safe — it only runs as far as you ask.

function* abc() { yield "a"; yield "b"; }
const it = abc();
console.log(it.next().value); // a
console.log(it.next().value); // b

Why it matters: generators model streams, pagination and endless sequences without building huge arrays.