SieveOfEratosthenes.js

'use strict';

const primeSieve = (n) => {
  const p = (new Array(n)).fill(1);
  for (let i = 2; i <= n; ++i) {
    for (let j = i * i; j <= n; j += i) {
      p[j] = 0;
    }
  }
  return p.map((i, x) => i ? x : i).filter(i => i);
}

const primesForLoop = (n) => {
  const p = (new Array(n)).fill(1);
  const o = [];
  for (let i = 2; i <= n; ++i) {
    for (let j = i * i; j <= n; (j += i)) {
      p[j] = 0;
    }
  }

  for (let x = 0; x < n; x++) {
    if (p[x]) {
      o.push(x);
    }
  }
  return o;
}


console.time('prime map/filter');
console.log(primeSieve(400).pop());
console.timeEnd('prime map/filter');

console.time('prime for loop');
console.log(primesForLoop(10000).pop());
console.timeEnd('prime for loop');