MongoDB and Node.js connection

https://zetcode.com/javascript/dotenv/

https://www.mongodb.com/languages/mern-stack-tutorial

https://attacomsian.com/blog/nodejs-mongodb-local-connection

https://stackoverflow.com/questions/68958221/mongoparseerror-options-usecreateindex-usefindandmodify-are-not-supported

https://mongoosejs.com/docs/connections.html

https://stackoverflow.com/questions/13190370/how-to-remove-duplicates-based-on-a-key-in-mongodb

https://stackoverflow.com/questions/62092955/how-do-i-remove-duplicates-in-mongodb-based-on-multiple-fields