JSFiddle - React, Tailwind, and code Playground

JavaScript

var is_prime = function(n) {
  if (n == 1) {
    return true;
  }
  if (n == 2) {
    return true;
  }
  
  for (var i = 2; i < n; i++) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}

var list_of_primes = function(n) {
  
  var list2 = [];
  
  for (var i = 2; i < n; i++) {
    if (is_prime(i)) {
      list2.push(i);
    }
  }
  return list2;
}
confirm(list_of_primes(1000))