Interactive Pages with Javascript project not working

var taskInput = document.getElementById("new-task"); //new task
var addButton = document.getElementsByTagName("button")[0]; //first button
var incompleteTasksHolder = document.getElementById("incomplete-tasks"); //incomplete t
var completedTasksHolder = document.getElementById("completed-tasks"); //completed
//Add a new task
var createTaskElement = function(taskString) {
//Create a new list item with the text from #new-task:
  var listItem = document.createElement("li");
   //Input (checkbox)
  var checkBox = document.createElement("input");
   //label
  var label = document.createElement("label");
   //input (text)
  var editInput = document.createElement("input");
   //button.edit
  var editButton = document.createElement("button");
   //button.delete
  var deleteButton = document.createElement("button")
   //Each elements, needs modified and appended  
  listItem.appendChild(

  )
  listItem.appendChild(checkbox); 
    listItem.appendChild(label);
    listItem.appendChild(editInput);
    listItem.appendChild(editButton); 
    listItem.appendChild(deleteButton); 
   //When a button is pressed
 incompleteTasksHolder.appendChild(listitem);
   //You create a task

}
var ajaxRequest = function() {
  console.log("AJAX request");
}

      addButton.addEventListener("click",addTask);
       addButton.addEventListener("click",addTask);
//Edit an existing task
var editTask = function() {
  console.log("Edit task...");
    var listItem = this.parentNode;
    var editInput = listItem.querySelector("");
    //if the class of the parent is .editMode
    //switch from .editMode

//Delete an existing task
listItem.classList.toggle(editMode");

//Mark a task as complete
//Mark a task as incomplete

var bindTaskEvents=function(taskListItem,checkBoxEventHandler){
}




//cycle over incompleteTaskHolder ul

//Delete an existing task
var deleteTask = function() {
  console.log("Delete task......");
 var listItem = this.parentNode;
 var editInput = listItem.parentNode;

  //Remove the parent list item from the ul
ul.removeChild(listItem);
}
//Mark task as complete
var taskCompleted = function() {
  console.log("complete task...");
   var listItem = this.parentNode;
  completedTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem,taskIncomplete);
  //When the checkbox is checked
  //Append the task list item to the #completed-tasks
}
//Mark task as incomplete
var taskIncomplete = function(){
  console.log("task incomplete...");
  //When the checkbox is unchecked
  //Append the task list item to the #incomplete-tasks
}


var bindTaskEvents = function(taskListItem, checkBoxEventHandler){
  console.log("Bind list item events");
    //select its children
    //bind deleteTask to delete button
    //bind taskCompleted to checkbox
}
//Set the click handler to the addTask function
addButton.onclick=addTask;

    //cycle over incompleteTaskHandler ul list items
for(var i=0; i< incompleteTaskHolder.children.length; i++){ 
  bindTaskEvents(incompleteTaskHolder.children[1], taskCompleted);

    //for each list item
    //bind events to list item's children (taskCompleted)

}  
     //cycle over completeTaskHandler ul list items
    for(var i=0; i< completedTaskHolder.children.length; i++){
    //for each list item
    bindTaskEvents(completedTaskHolder.children[1], taskIncomplete);{
    }