document.addEventListener("DOMContentLoaded", function () {
var todo = Object.create(null);

todo.newTodo = function (evt) {
    evt.preventDefault();
    var newTodo = document.getElementById("todo-item").value;
    var ul = document.getElementById("todo-view");
    var li = document.createElement("li");
    li.innerHTML = newTodo + '<span>x</span>';

    //using tertnary operator to add items to top of list if other items already exist
    (ul.childElementCount == 0) ? ul.appendChild(li) : ul.insertBefore(li, ul.firstChild);

    document.getElementById('todo-item').   value = "";

    var span = li.getElementsByTagName("span");

    span[0].addEventListener("click", todo.deleteTodo, false);
}

var todoCache = [];

todo.deleteTodo = function () {
    todoCache.push(this.parentNode);

    console.log(todoCache);

    this.parentNode.parentNode.removeChild(this.parentNode);

    return todoCache;
}

todo.undoDelete = function () {
    var ul = document.getElementById("todo-view");

    if (todoCache.length > 0 ) {
        var lastTodo = todoCache.length - 1;

        ul.appendChild(todoCache[lastTodo]);

        todoCache.pop();
    }
}

var todoSub = document.getElementById("submit-item");

todoSub.addEventListener("click", todo.newTodo, false);

var undo = document.getElementById('undo');

undo.addEventListener("click", todo.undoDelete, false);});