Lesson 17 — Closures

Functions that remember

A closure is a function that keeps access to the variables of the place where it was created — even after that outer function has finished. Each call to makeCounter() creates a fresh, private c.

function makeGreeter(name) {
  return () => "Hi, " + name;   // remembers name
}
makeGreeter("Sam")();   // "Hi, Sam"

++c adds 1 and gives back the new value.

Why it matters: closures give you private state without classes — they are behind counters, event handlers and React hooks.