Design:

Very good and beautiful

A lot of features. If you don't want to write everything from scratch, this is the way to go

Code-wise:

However, the quality is what I have to put 4 stars instead of 5

First of all, no Typescript, which leads to a buggy app

Secondly, he uses his own npm package to manipulate the DOM, Modal, etc...

To add things worse, the modal module is added to the global scope (window object). It is a bad practice, anti-pattern

Also, instead of creating a custom hook, the app mutates the object, JSON.stringify, and JSON.parse again (just have a look at the nestedMenu function)

I don't say it doesn't work, but how it is written irritates me