how checkbox event bind to checkBoxEventHandler?

//Problem: User interaction doesn't provide desired results.
//Solution: Add interactivty so the user can manage daily tasks.

var taskInput = document.getElementById("new-task"); //new-task
var addButton = document.getElementsByTagName("button")[0]; //first button
var incompleteTaskHolder = document.getElementById("incomplete-tasks");//incomplete-tasks
var completedTaskHolder = document.getElementById("completed-tasks");//completed-tasks


//functions*****************************************************************************//

//new task list item
var createNewTaskElement = function(taskString){
  //cereate list item
  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 element needs be modifing

  //each element needs appending
  listItem.appendChild(checkBox);
  listItem.appendChild(label);
  listItem.appendChild(editInput);
  listItem.appendChild(editButton);
  listItem.appendChild(deleteButton);
  return listItem;
}

//add a new task
var addTask = function(){
 var listItem = createNewTaskElement("Some new task");

 //append listItem to incompleteTaskHolder
  incompleteTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem,taskCompleted);
}

//edit an exsisiting task
var editTask = function(){
  console.log("e");
}

//delete an existing task
var deleteTask = function(){
  console.log("d");
}

//mark a task as complete
var taskCompleted = function(){
  var listItem = this.parentNode;
  completedTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem,taskIncomplete);
}

//mark a task as incomplete
var taskIncomplete = function(){
  //append the task list item to the #completed-task
  var listItem = this.parentNode;
  incompleteTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem,taskCompleted);

}

var bindTaskEvents = function (taskListItem,checkBoxEventHandler){
  console.log("bind list item events");
  //select taskListItem's children
  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;
}
//set the click handler to the addTask function
addButton.onclick = addTask;

//cycle over incompleteTasksHolder ul list items
for(var i =0; i < incompleteTaskHolder.children.length; i++){
  //bind events to list item's children(taskCompleted)
  bindTaskEvents(incompleteTaskHolder.children[i],taskCompleted);
}

//cycle over completeTasksHolder ul list items
for(var i =0; i < completedTaskHolder.children.length; i++){
  //bind events to list item's children(taskCompleted)
  bindTaskEvents(completedTaskHolder.children[i],taskIncomplete);
}