Generic REST Library For SharePoint CRUD Operation

For one of my clients, I was working on developing custom forms to interact with SharePoint lists and document libraries.
In that project, there were so many forms to be developed. So, I decided to develop one generic library that can be reused to perform operations using REST API.
The aim of this library is to create a generic set of methods as well, keeping one thing in mind that it should be enhanced easily to include more features.
In this library, there are a total 4of four files.
  1. ListManager.js
    This file is used to specify list columns we are working with.

  2. ListUtility.js
    This file contains all generic methods.

  3. Main.js
    Use this file to write application logic. This will be the main file referenced in our page, the rest of the files are loaded from Main.js itself.

  4. Utility.js
    It can be used to specify constants as well as utility methods.
I have also provided detailed information and instructions in attached zip file.