Backend details

Only on Refresh or Onload, whole DOM gets rendered.
Task like add, delete, toggle and edit-save do not rerender whole DOM, ONLY THE specific task-item.

UTILITY Functions on refresh or onload

* renderFromTaskArray() : totally re-render the DOM from array for refresh action 
* removeAllTask() : to remove all the task for re-render for refresh action 

UTILITY Functions

* initTaskInArray() : initialize the Task Array from localstorage  
* renderTaskList() : create "task-item" element from the Task Array, append to "added-list" or "done-list" container  
* updateLocalStorage() : to update the local storage  

EVENTLISTENERs

* ToggleTask() changes "UNDONE" to "DONE" and vice-versa 
* EditTask() changes the text of the task
* SaveItem() save changes from EDIT TASK operation 
* DeleteTask() deletes the task 

The edit and add function handle empty string input
The toggle task toggles "completed" between true and false, (done/ undone)