This system is working without using the file system of node. And I'm also using Thunder client (VS Code extension) for sending request, but you can also use Postman.

First create an ordinary Node JS application.

This is my folder structure and package.json file. I will be using these packages to do the work.

Go to Cloudinary and create a free account. After creating an account, you will find CLOUDINARY_NAME, CLOUDINARY_API_KEY, CLOUDINARY_API_SECRET in your account dashboard.

1# .env file
=> This file will contain all of the secret you don't want to show others

2# cloudinary.js file
=> Connects your application to cloudinary. Remember to use dotenv

3# cloudinaryAccountStorage.js file
=> This file will create a seperate folder to store all of your images in Cloudinary.

4# people.js file
=> People schema and people model for mongoose to store data in DB.

5# message.js file
=> Message schema and message model for mongoose to store data in DB.

6# server.js file
=> Every file is connected here. Remember to import and use dotenv.

7# uploadRouter.js file
=> Main routing file of this application. Send different request to different path.

8# imageUploader.js file
=> Universal image uploader file. Maximum file size, maximum file number, file type, and validation can control using this function.

9# avatarUpload.js file
=> Sending params to imageUploader.js for file size, file number and file type with error message. Most of the tutorial uses upload.single(), upload.array(), upload.fields() but I'm using upload.any()() to give you some idea how it works

10# attachmentUpload.js file
=> Sending params to imageUploader.js for file size, file number and file type with error message. Most of the tutorial uses upload.single(), upload.array(), upload.fields() but I'm using upload.any()() to give you some idea how it works

11# uploadController.js file
=> Structure and async function name of controller function. This file control upload and remove images from Cloudinary. It also sends json data to database.

11.1# addUser function of uploadController.js
=> Upload single image to Cloudinary and send public_id, secure_url to database of cloudinary upload.

Result of addUser function

11.2# deleteUser function of uploadController.js
=> Remove single image from Cloudinary also remove from database.

Result of deleteUser function

11.3# sendMessage function of uploadController.js
=> Upload multiple images to Cloudinary and send public_id, secure_url to database as an object of different cloudinary upload.

Result of sendMessage function

11.4# removeMsgAndAttachments function of uploadController.js
=> Remove multiple images from Cloudinary also remove from database.

Result of removeMsgAndAttachments function

Git repo of this code.
Thank you all.