function createMongoDb(callback) {
    var Db = require('mongodb').Db;
    var Server = require('mongodb').Server;
    var dbName = 'testdb', dbHost = 'localhost', dbPort = '27017';
    var dbUser = 'testuser', dbPassword = 'testpassword';

    var db = new Db(dbName, new Server(dbHost, dbPort));

    // Connect to the database
    db.open(function (err, db) {
        if (err) {
            console.log(err);
            callback();
        }
        else {
            // Authenticate user (basically check if user exists)
            db.authenticate(dbUser, dbPassword, function(err, result) {
                // If error authenticating:
                // user doesn't exist, so create user
                if (err){
                    db.addUser(dbUser, dbPassword, {roles: ["dbOwner"]}, function(err, result) {
                        if (err){
                            console.log(err);
                        }

                        // close database connection
                        db.close();
                        callback();
                    });
                }
                // Otherwise, user exists
                else{

                    // close connection
                    db.close();
                    callback();
                }
            });
        }
    });
}

// Calls function createMongoDb
createMongoDb(function() {
    // Do something here
   console.log('MongoDB database created');
});