function evShowleap() {
var vlez = document.querySelector("input[type=number]").value;
var ekran = document.querySelector("#ekran");
if(!vlez.trim()) {
ekran.innerHTML = "enter a year";
return;
}
var rezultat = leapyear(vlez);
if (rezultat === true) {
ekran.innerHTML ="Year " + vlez + " is a Leap Year";
} else {
ekran.innerHTML ="Year " + vlez + " is not a Leap Year";
}