Do you know what will be the output of this code? function counter() { let count = 0; return () => ++count; } const inc = counter(); inc(); inc(); console.log(inc());

How does a closure counter work in JavaScript?

Do you know what will be the output of this code?

JavaScript

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

const inc = counter();
inc();
inc();
console.log(inc());

Show answer and explanation

The answer is 3.

The arrow function is a closure: it keeps a reference to count even after counter() has returned. Every call increments the same variable.