<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){// 將以后與當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>