text: var lis = document.querySelectorAll("li");
  
  for (var i = 0; i < lis.length; i++) {
      lis[i].addEventListener("mouseover", function () {
          this.classList.add("selected");
      });
  
      lis[i].addEventListener("mouseout", function () {
          this.classList.remove("selected");
      });
  
      lis[i].addEventListener("click", function () {
          this.classList.toggle("done");
      });
  
  }
  