筛选素数/筛选质数

//筛选 0-num的素数
function primes(num) {
  var s = [];
  //初始化0-num的值
  for (var i = 0; i <= num; i++) {
    s.push(i);
  }
  //筛掉不合适的值
  delete s[0];
  delete s[1];
  for (var j = 2; j <= num; j++) {
    if (!s[j]) continue;//如果 j 是合数
    for (var k = 2; j * k <= num; k++) {
      delete s[j * k];//筛掉合数
    }
  }
  //去掉被删掉的值
  return s.filter(function(x) {
    return x;
  })
}

var res = primes(10)
console.log(res);