The Node.js drivers for MongoDB contain all of the necessary network code to establish and break connections with MongoDB running on your local or remote machine.

You need to include a reference to the native driver in your code and specify the URL of the database to connect to.

Here's a simple example that connects to the database and promptly disconnects:

var mongo = require('mongodb').MongoClient;

var url = 'mongodb://localhost:27017/test';

mongo.connect(url, function(error, db) {
  console.log("mongo.connect returned " + error);
  db.close();
});

Let's break this down line by line.

The first line includes the native driver implementation for Mongo in your Node.js application, and extracts a reference to the MongoClient object it defines. This object contains the basic interface you need to interact with...