let from = document.querySelector('.from'),
    to = document.querySelector('.to'),
    trigger = document.querySelector('.trigger'),
    result = document.querySelector('.response');


function getBiggestPrime(from, to){
  var divisors = [],
      primes = [];
      for(var i = from; i <= to; i++){
          for(var j = 1; j <= i; j++){
            if(Number.isInteger(i/j)){
              divisors.push(j);
            }
          }
        //alert(divisors);
        if(divisors.length == 2){
          primes.push(i);
        }
        divisors = [];
      }
  //alert(primes);
  result.innerHTML = "Najwiekszą liczbą pierwszą zbioru "+from+"-"+to+" jest "+Math.max.apply(Math, primes);
  primes = [];
}
trigger.addEventListener('click', function(ev){
  getBiggestPrime(from.value,to.value);
});