function isPrime(num){
  //If number is equal to 1 or 2, return true;
  if(num == 1 || num == 2){
    return true;
  }
  //Looping from 2 to the given number
  for(x = 2; x < num; x++){
    //If the given number is divisible by any number except 1, return false.
    if(num % x == 0){
      return false;
    }
  }
  return true;
}

function reverse(num){
  //The number is converted into string to modify it
  var string = num.toString();
  //The converted group of number is split into separate number. eg. 123 => 1,2,3
  var split = string.split("");
  //Reverse the split numbers using reverse method. eg. 1,2,3 => 3,2,1
  var reverse = split.reverse();
  //Join the separated number eg. 3,2,1 => 321
  var join = reverse.join("");
  //Converted the string into number again
  var number = parseInt(join);

  return number;

  //Can be compress into one line.
  //return parseInt(num.toString().split("").reverse().join(""));

  /*There is also a traditional way to reverse it:
    num = num.toString();
    var str = "";
    for(x = num.length - 1; x >= 0; x--){
        str += num[x]
    }
    return parseInt(str);
  */
}

function emirp(num){
  //If both of the number and its reversed version is prime, return true
  if(isPrime(num) && isPrime(reverse(num))){
    return true;
  }
  else{
    return false;
  }
}

window.onload = function(){
  var min = prompt("Your min number?");
  var max = prompt("You max number?")

  if(min <= max){
    while(min <= max){
      document.write(min + " : " + emirp(min) + "<br />");
      min++;
    }
  }
  else{
    alert("Min is greater than max. Error")
  }
}