About Prim(关于质数的一些操作)

generatePrimes.js

function generatePrimesList(num) {
    let ret = [];
    if (num >= 2) 
        ret.push(2);
    for (let i = 3; i <= num; i++) {
        let flag = true;
        for (let j = 0; j < ret.length; j++) {
            if (i % ret[j] === 0) {
                flag = false;
                break;
            }
        }
        if (flag) 
            ret.push(i);
        }
    return ret;
}
function generatePrimesList2(...nums) {
    let [num1, num2] = nums.sort((a, b) => a - b);
    let ret1 = generatePrimesList(num1);
    let ret2 = generatePrimesList(num2);
    let start = ret1.includes(num1) ? ret1.length - 1 : ret1.length;
    return ret2.slice(start);
}

isPrime.js

function isPrime(num) {
  if(num<=1) return false;
  let flag = true;
  for(let i=2;i<=Math.ceil(Math.sqrt(num));i++) {
    if(num%i===0 && num!==i) {
      flag = false;
      break;
    }
  }
  return flag;
}