JAVASCRIPT

JavaScript Data Privacy

let a = 0;
function sum() {
    function increaseSum() {

        // the value of a is increased by 1
        return a = a + 1;
    }
    return increaseSum;
}

const x = sum();
console.log(x()); // 1
console.log(x()); // 2
console.log(x()); // 3
a = a + 1;
console.log(a); // 4