JuniorTheoryCommon

What does the program print?

JavaScript

function makeCounter() {
    let count = 0;
    return () => {
        count += 1;
        return count;
    };
}
const a = makeCounter();
const b = makeCounter();
console.log(a(), a(), b());

1 2 1

Expecting 1 2 3: each call of makeCounter creates its own count, so b starts from zero and does not see the count of a.
Expecting 1 1 1: let count = 0 runs once per makeCounter call, not on each call of the returned function, so a keeps counting up.

What would a() return if you called it a third time?
How could two counters share one count?

Back to questions Open topic in roadmap →Answer it yourself — Quiz

Back to questions

JuniorTheoryCommon

What does the program print?

JavaScript

function makeCounter() {
    let count = 0;
    return () => {
        count += 1;
        return count;
    };
}
const a = makeCounter();
const b = makeCounter();
console.log(a(), a(), b());

1 2 1

Expecting 1 2 3: each call of makeCounter creates its own count, so b starts from zero and does not see the count of a.
Expecting 1 1 1: let count = 0 runs once per makeCounter call, not on each call of the returned function, so a keeps counting up.

What would a() return if you called it a third time?
How could two counters share one count?

Back to questions Open topic in roadmap →Answer it yourself — Quiz