What is a closure in JavaScript?

Question

What is a closure in JavaScript?

Answer

A closure is created when a function remembers the variables from its outer scope even after the outer function has finished executing.

function makeCounter() {
  let count = 0;
  return function () {
    count++;
    return count;
  };
}

const counter = makeCounter();
console.log(counter()); // 1
console.log(counter()); // 2

Here, the inner function “closes over” the count variable.

Real-World Example

Closures are used in React hooks, event handlers, and data encapsulation.

Quick Practice

Create a function createUser(name) that returns a function logging that name when called.

Summary

Closures let functions remember — they give JavaScript memory and encapsulation power.