main.js

var close = document.getElementsByClassName("close");
for (var i = 0; i < close.length; i++) {
  close[i].onclick = function() {
    var div = this.parentElement;
    div.style.display = "none";
  }
}
var list = document.querySelector('ul');
list.addEventListener('click', function(ev) {
  if (ev.target.tagName === 'LI') {
    ev.target.classList.toggle('done');}
  }, false);   
function newElement() {
    var li = document.createElement("li");
    var inputValue = document.getElementById("myInput").value;
    var t = document.createTextNode(inputValue);
    li.appendChild(t);
    if (inputValue === '') {
      alert("You must write something!");
    } else {
      document.getElementById("items").appendChild(li);
    }
    document.getElementById("myInput").value = "";

    var span = document.createElement("SPAN");
    var txt = document.createTextNode("\u00D7");
    span.className = "close";
    span.appendChild(txt);
    li.appendChild(span);

    for (i = 0; i < close.length; i++) {
      close[i].onclick = function() {
        var div = this.parentElement;
        div.style.display = "none";
      }
    }
}