1const mongoAtlasUri =
2  "mongodb+srv://username@gmail.com:password@cluster0.mkb94.mongodb.net/DB_NAme?retryWrites=true&w=majority";
3
4try {
5  // Connect to the MongoDB cluster
6  mongoose.connect(
7    mongoAtlasUri,
8    { useNewUrlParser: true, useUnifiedTopology: true },
9    () => console.log(" Mongoose is connected")
10  );
11} catch (e) {
12  console.log("could not connect");
13}

1// local conecation
2
3const mongoose = require("mongoose");
4
5mongoose
6  .connect("mongodb://localhost:27017/testdb")
7  .then(() => console.log("Connected to MongoDB..."))
8  .catch((err) => console.error("Could not connect to MongoDB...", err));
9

1mongoose.connect('mongodb://username:password@host:port/database?options...', {useNewUrlParser: true});