Steps to run this code-

1. copy all the folders in a master folder in your system.
2. install required libraries through npm . you can see list of them in package.json file
3. create a database named whatsapp in mongodb
4. create required collections and docs in it as written in init.js file and others
5. run index.js to start server
6. now you run this site in you browser by typing: localhost:8080/chats
7. done.

this is made without using react in mern stack