Code not working at all!

var taskInput = document.getElementById("new-task");
var incompleteTasksHolder = document.getElementById("incomplete-tasks");
var completeTasksHolder = document.getElementById("completed-tasks");
var addButton = document.getElementsByTagName("button")[0];

var createNewTaskElement = function(taskString) {
var listItem = document.createElement("li");
var checkBox = document.createElement("input");
var label = document.createElement("label");
var editInput = document.createElement("input");
var editButton = document.createElement("button");
var deleteButton = document.createElement("button");

checkBox.type = "checkbox";
editInput.type = "text";

editButton.innerText = "Edit";
deleteButton.innerText = "Delete";

editButton.className = "edit";
deleteButton.className = "delete";

label.innerText = taskString;

listItem.appendChild(checkBox);
listItem.appendChild(label);
listItem.appendChild(editInput);
listItem.appendChild(editButton);
listItem.appendChild(deleteButton);

return listItem;
}

var addTask = function() {
  console.log("Add task");
  var listItem = createNewTaskElement(taskInput.value);
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
  taskInput.value = "";
}

var editTask = function() {
  var listItem = this.parentNode;
  var editInput = listItem.querySelector("input[type=text");
  var label =  listItem.querySelector("label");                       
  var containsClass = listItem.classList.contains("editMode");         
  if(containsClass) {
    label.innerText = editInput.value;
  }
  else
  editInput.value = label.innerText;
}

listItem.classList.toggle("editMode");

var deleteTask = function() {
var listItem = this.parentNode;
var ul = listItem.parentNode;
ul.removeChild(listItem);
}

var taskCompleted = function() {
var listItem = this.parentNode;
completedTasksHolder.appendChild(listItem);
bindTaskEvents(listItem, taskIncompleted);
}

var taskIncompleted = function() {
var listItem = this.parentNode;
incompleteTasksHolder.appendChild(listItem);
bindTaskEvents(listItem, taskCompleted);
}

var bindTaskEvents = function(taskListItem, checkBoxEventHandler) {
  console.log("bind list items");
  var checkBox = taskListItem.querySelector("input[type="checkbox]");
  var editButton = taskListItem.querySelector("button.edit");
  var deleteButton = taskListItem.querySelector("button.delete");

  editButton.onclick = editTask;
  deleteButton.onclick = deleteTask;
  checkBox.onchange = checkBoxEventHandler;
}

addButton.onclick = addTask;

  for(var index = 0; index < incompleteTasksHolder.children.length; index++) {
        bindTaskEvents(incompleteTasksHolder.children[index], taskCompleted);
}

  for(var index = 0; index < completeTasksHolder.children.length; index++) {
        bindTaskEvents(completeTasksHolder.children[index], taskIncompleted);
}