JSFiddle - React, Tailwind, and code Playground

JavaScript

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