JSFiddle - React, Tailwind, and code Playground

JavaScript

var val = sessionStorage.getItem("test");
if (val==null){
  var a = prompt("Zadej hodnotu");
  sessionStorage.setItem("test", kokot);
    alert ("Nastaveno");
} else {
  alert("Ulozena hodnota: "+val);
    alert("Klic:"+sessionStorage.key(0));
//    sessionStorage.removeItem("test");
}