If you check the files that you ended up with in the previous chapter, you will see that the backend/API.js file is quite big. It will get more and more difficult to work with. We are going to refactor this part of our system.

We have a bunch of helper methods that are used all over the route handlers. Functions such as response, error, and getDatabaseConnection may be placed in an external module. We will create a new api folder under the backend directory. The newly created helpers.js file will host all these utility functions:

// backend/api/helpers.js
var MongoClient = require('mongodb').MongoClient;
var querystring = require('querystring');
var database;

var response = function(result, res) { ... };
var error = function(message, res) { ... };
var getDatabaseConnection = function(callback) { ... };
var processPOSTRequest = function(req, callback) { ... };
var validEmail = function(value) { ... };
var getCurrentUser = function(callback, req, res) { ... };

module.exports...