Get all prime number up to N

sieve.js

function sieve (n) {
  let all = [...Array(n).keys()].map(x => true)
  for (let i = 2; i <= Math.sqrt(n); i += 1) {
    if (all[i]) {
      for (let j = i * i; j < n; j += i) {
        all[j] = false
      }
    }
  }
  return all.map((x, i) => {
    if (x && i > 1) return i 
  }).filter(x => !!x)
}