docs: function getPrimes(limit) {
      var sieve = new Array(limit);
      var n, j, k;
      var last = Math.floor(Math.sqrt(limit));
      for (n=2; n < limit; n++) {
          sieve[n] = true;
      }
      for (n=2; n <= last;) {
          for (j= n+n; j < limit; j += n) {
              sieve[j] = false;
          }
          for (j=1; j < last; j++) {
              k = n+j;
              if (sieve[k]) {
                  n = k;
                  break;
              }
          }
      }
      var primes = [];
      for (n=2; n < limit; n++) {
          if (sieve[n]) {
              primes.push(n);
          }
      }
      return primes;
  }