How to Connect Mongo db with Node JS & Express JS

Setting Up a Node.js Project
Initialize Node.js Project: Create a new folder for your project and run npm init to initialize a new Node.js project.

Install Dependencies

npm install express mongoose

Connecting MongoDB with Mongoose
Set up a basic Express application in your index.js file:

const express = require("express");
const app = express();
const PORT = process.env.PORT || 3000;
require("./dbconnection.js")

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

Set up a Db connection file dbconnection.js file:

const mongoose = require("mongoose");
const express = require("express");
require("dotenv").config();
const app = express();
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
mongoose.connect(process.env.MONGODB_URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

const db = mongoose.connection;
db.once("open", (_) => {
  console.log("Database connected:", process.env.MONGODB_URI);
});

db.on("error", (err) => {
  console.error("connection error:", err);
});

by replacing process.env.MONGODB_URI with you own url

Go to terminal and type npm start

npm start

Congratulatios! you db has been connected now you can start playaround it