Prime number calculator used as part of a debugging tutorial on talktotheduck.dev

prime-app.js

const MAX_NUMBER = 10 ** 9;
let cnt = 0

function isPrime(num) {
    if (num === 2) {
        return true;
    }
    if (num < 2 || num % 2 === 0) {
        return false;
    }
    for (let i = 3; i * i <= num; i += 2) {
        if (num % i === 0) {
            return false;
        }
    }
    return true;
}

function countPrimes(i) {
    if (isPrime(i)) {
        cnt++;
    }
    if (i < MAX_NUMBER) {
        setTimeout(() => countPrimes(++i));
    } else {
        console.log("Total number of primes: " + cnt);
    }
}

console.log("Starting to count prime numbers...");

setTimeout(() => countPrimes(2));