$ npm init 
$ npm i express@4 
$ sudo npm install -g nodemon 

* JSON.parse() method used to convert the json file to object
* get status: 200 (OK)
* post status: 201 (created)
* Error status: 404 (Not Found)
* Null status: 202 (No content)
* Internal Server Error: 500 
* Missing Params: 400 (bad request)

* Express Middleware :- Which allow us to read the data from the user(postman body) and write our document.
  app.use(express.json());

//to convert the id into int
  const id=parseInt(req.params.id);
  or
  const id= req.params.id *1; 

patch method :- Update the only desired value from the database.
put method :- Update the whole database 
delete method :- Delete the whole database

* Custom middleware : Every time it will be execute whenever any request will be send.
* morgan : used as a middleware to identify the request.
  $ npm i morgan
* Install morgan only for developemnt env
  $ npm i morgan --save-dev  

MVC Model: Model-Veiw-Controller
Serving Template: Access the static files using express
app.use(express.static(`${__dirname}/nft-data/img`));

.env file :
  $ npm i dotenv
// To start the application in development environment
  $ npm start
// To start the application in production environment
  $ npm run start:prod   

* MongoDB Connection :
  $ npm install mongodb
  $ npm i [email protected]

* Remove the folders and files from git
  $ git rm -r "folder name"
  $ git rm "file name"

* Add the config files in .gitigone file

  $ echo ".env" >> .gitignore
  $ git rm --cached .env
  $ git add .gitignore