express Js :

https://www.youtube.com/watch?v=cMbJ8hatqJ8&list=PLyuRouwmQCjne87u8XUdOM5oCl7vI2vVL

Node.js Express and MongoDB: Login and Registration example

https://www.bezkoder.com/node-js-express-login-mongodb/

OAuth 2.0 and OpenID Connect :

https://www.youtube.com/watch?v=996OiexHze0

https://www.telerik.com/blogs/implementing-oauth-2-using-node-js

https://www.youtube.com/watch?v=Qt3KJZ2kQk0

DIR_Structure

views  --> contains views rendered by view engines i.e. ejs
models --> Database models/schema
public --> To serve static files such as images, CSS files, and JavaScript 
           files, use the express.static built-in middleware function in Express.
routes --> contains different routes for REST style urls
config --> contains configuration for auth and Database

controllers --> Server side controllers to implement different functionalities
middlewares --> contains middlewares to support controllers

node_modules --> contains dependencies for the project

.env file:

contains environment variable and secrets (meant to be stored locally and not be made public)
    ACCESS_TOKEN_SECRET=[64-byte secret in hex]
    PORT=3000
    USER_NAME=[mongo_db_username]           
    DB_PASSWORD=[mongo_db_password]
    GOOGLE_CLIENT_ID=[google-clientId].apps.googleusercontent.com
    GOOGLE_CLIENT_SECRET=[google-client-secret]
    GOOGLE_OAUTH_REDIRECT=[redirect-to-server-side-access-code-handler]

Start Node.js in production

https://maximorlov.com/start-node-js-in-production/