hwo to make ana array of prime numbers in javascript

1function sort_prime(num) {
2
3  var prime_num1 = [],
4      prime_num2 = [];
5  for (var i = 0; i <= num; i++) {
6    prime_num2.push(true);
7  }
8  for (var i = 2; i <= num; i++) {
9    if (prime_num2[i]) {
10      prime_num1.push(i);
11      for (var j = 1; i * j <= num; j++) {
12        prime_num2[i * j] = false;
13      }
14    }
15  }
16
17  return prime_num1;
18}
19
20console.log(sort_prime(5))