JavaScript Closures, Scope, and Hoisting Explained

These three concepts are the foundation of JavaScript. Understanding them makes you a better developer and interview candidate.

Closures

A closure is when a function retains access to its outer scope even after the outer function has returned.

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

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

Hoisting

console.log(name); // undefined
var name = 'Jeevan';

console.log(age); // ReferenceError
let age = 25;

Final Thoughts

Closures power many patterns in JavaScript including callbacks, data privacy, and factory functions. Master them and interviews become much easier.

Happy Coding!