LeetCode: Count Primes Solution

1/**
2 * @param {number} n
3 * @return {number}
4 */
5var countPrimes = function (n) {
6  return sieveOfEratosthenes(n).filter(Boolean).length
7}
8
9const sieveOfEratosthenes = n => {
10  const prime = new Uint8Array(n).fill(true)
11  prime[0] = prime[1] = false
12  for (let i = 2; i * i <= n; i++) {
13    if (prime[i]) {
14      for (let k = i * i; k <= n; k += i) {
15        prime[k] = false
16      }
17    }
18  }
19  return prime
20}