JavaScript 计算小于非负数 n 的素数数量算法示例

基于标记法的素数计数实现

<script>
  var countPrimes = function(n) {
  let flagArray = [],
    result = 0;
  for(let i = 2; i < n; i++){
    if(flagArray[i] === undefined){
      flagArray[i] = 1;
      result++;
      let j = 2;
      while(i * j < n){// 将以后与当前值能整除的排除掉
        flagArray[i * j] = 0;
        j++;
      }
    }
  }
  return result;
};
console.log(countPrimes(10));
console.log(countPrimes(100));
</script>

<script>
function PrimesList(m,n){
  var rel = [];
  for (var i = m; i < n ; i++) {
    for (var j = 2; j < i; j++) {
      if (i%j==0)
        {
          break;
        }
      else{
        rel.push(i);
      }
    }
  }
  return rel
}
console.log(PrimesList(100,200));
</script>