Javascript + localstorage = todo list

Hi everyone!
This is my first post here and this to-do list is one of my recent projects, I would be glad to know your review about it.

The code is a little complex to read because there are many lines of codes ( ~870 JS ). I've used so many functions and handled many events.

This app needs no server-side coding, everything happens client-side.

• It works with localstorage and saves your data there
• Report if you discovered UX issues

NOTE: resize your browser to work with the app if you're on desktop.

hmht.ir/page/todo

And here is the source code