https://www.webareal.cz/js/price_to_month.js?_=2020-01-31-1130

1$( document ).ready(function()
2{
3  //pole s mutacemi, kreré se budou zaokrouhlovat na 2 desetinná místa
4  var round = ["sk","es", "gb", "pl", "ro", "de"].indexOf(id_language) >= 0 ? 2 : 0;
5
6  var calcPricePerMonth = function(payment, months) {
7    var price = parseFloat(payment) / parseInt(months);
8
9    return price.toFixed(round);
10  };
11
12  var updatePricePerMonth = function(el) {
13    var selected = el.options[el.selectedIndex];
14    var target = document.getElementById(el.dataset.update);
15    if(target) {
16      target.innerText = calcPricePerMonth(el.value, selected.dataset.monthCount);
17    }
18  };
19
20  var planOptions = document.querySelectorAll(".plan__options");
21  planOptions.forEach(function(el) {
22    el.addEventListener("change", function(e) {
23      updatePricePerMonth(e.target);
24    });
25    el.dispatchEvent(new Event("change"));
26  });
27});