решето Эратосфена

eratosfen.js

// let ticks = null;

function primes(n) {
    const a = new Array(n);
    const ret = [];
    a.fill(true);
    // ticks = 0;
    for (let i = 2; i <= n; i++) {
        // ticks++;
        if (a[i]) {
            ret.push(i);
            for (let j = i*i; j < n; j+=i) {
                a[j] = false;
                // ticks++;
            }
        }
    }
    // console.log('TICKS: ', ticks);
    return ret;
}
let ticks = null;

function primes(n) {
    const a = new Array(n);
    const ret = [];
    a.fill(true);
    ticks = 0;
    for (let i = 2; i <= n; i++) {
        ticks++;
        if (a[i]) {
            ret.push(i);
            for (let j = i*i; j < n; j+=i) {
                a[j] = false;
                ticks++;
            }
        }
    }
    console.log('TICKS: ', ticks);
    return ret;
}