Using a nodejs script to connect to localhost 27017

I have MongoDB installed and I can view it through Compass. Now i want to create an Express script that will connect to MongoDB and show data on my browser. I am working through the Web Developers Bootcamp on Udemy, and so far i have this:

var express = require('express');
var app = express();

// "/" => "Hi there"
app.get('/', function(req, res) {
  res.send('hi there');

app.listen(27017, function() {
  console.log('i heard you');

When I run this from PowerShell, using: node ./app.js, I get “i heard you” (from my listen function above. So I am apparently “connected” to port 27017. Now I want to see “i heard you” in the browser. I assume it should look, in browser address bar,, with my “i heard you” in the browser window.

So sorry if this is all over the place.

Thanks for any help!

Okay, this about using Express (a web framework for NodeJS) and MongoDB. I put together this basic code from samples at: Getting started with Express and Quick Start Examples with MongoDB NodeJS Driver

The code works fine, and try to follow it by perusing the code comments.

// app.js (or index.js)
const express = require('express')
const app = express()
const port = 3000

app.listen(port, () => console.log('Example app listening on port ' + port))

// This line of code is for printing Hello World! in the browser,
// when you enter in the browser url bar: http://localhost:3000/
app.get('/', (req, res) => res.send('Hello World!'))

// This variable is populated in the findDocuments function (see below "Using Mongo")
var mongoDocsToDisplay = null;

// This line of code will print the collection's documents in the browser,
// when you enter in the browser url bar: http://localhost:3000/mongo
app.get('/mongo', (req, res) => res.send(

// Using MongoDB:

const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
const url = 'mongodb://localhost:27017';

const dbName = 'test';
const client = new MongoClient(url, { useNewUrlParser: true, useUnifiedTopology: true } );

// Connect to MongoDB server, run the findDocuments function and close the connection.
client.connect(function(err) {

    assert.equal(null, err);
    console.log('Connected successfully to MongoDB server on port 27017');
    const db = client.db(dbName);

    findDocuments(db, function() {

const findDocuments = function(db, callback) {

  const collection = db.collection('test');

  collection.find({}).toArray(function(err, docs) {
    assert.equal(err, null);
    console.log('Found the following documents:');
	mongoDocsToDisplay = docs;
1 Like

This is helpful! Thanks!

Your Node application is actually listening to port 27017. Since 27017 is the default port used by a local MongoDB installation, typically you’d use a different port for your application (such as 3000 in @Prasad_Saya’s example).

The correct reference would be http://localhost:27017 for your original config or http://localhost:3000 for Prasad’s example. Your original URI is requesting the contents of the /localhost path from the host on port 27017, which probably isn’t what you were expecting.

The console.log() command logs to the scripting console. To return a response to a browser/client using Express, you should call methods on Express’ response object. For example, your original script used res.send().


1 Like