Javascript – My mongodb database is not getting connected with my express node server using mongoose

I am getting started with backend and just keep getting the same error.
This is my server.js –>

// Step 1 create a folder backend
// Step 2 npm init -y
// Step 3 open in VS Code
// Step 4 npm i express
// Step 5 create server.js

// Server Instantiate
const express = require("express");
const app = express();

// used to parse req.body in express -> PUT or POST
const bodyParser = require("body-parser");
// Specifically parse JSON data and add it to the req.body object
app.use(bodyParser.json());

// Server started on port 3000
app.listen(3000, () => {
  console.log("Server started at port no 3000");
});

// A get request for route '/'
app.get("/", (req, res) => {
  res.send("Hello Jee Kaise hai aap");
});

// '/' route sends a response when accessed via GET
// This is a GET request --> app.get()

app.post("/cars", (req, res) => {
  const { name, brand } = req.body;
  console.log(name);
  console.log(brand);
  res.send("car submitted successfully");
});

const mongoose = require("mongoose");
mongoose
  .connect("mongodb://localhost:27017/newDB", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then(() => {
    console.log("connection successful");
  })
  .catch((error) => {
    console.log("error came");
  });

Every time I am running this code in my terminal using "node server". I am getting the "error came" as output from .catch block .
Though my Mongodb server and express server is live but still I am unable to get connected with my database .
I am using Mongodb compass by the way. And the mongoose is also installed properly.

Please help me to come out from this error. I tried a lot but never getting "connection successful" as output.