Let's start our journey through Node.js with a Node.js installation. Installers are available for both Windows and macOS at https://nodejs.org/en/download/.  At the time of writing, Node.js 10 has just been released as the current version, and is about to become the next Long Term Support version, in August 2018. Linux users can either build Node.js from the available Linux binaries or make use of their package manager, as Node.js is available with most of the popular package repositories for different Linux distributions. For instance, Ubuntu and other Debian-based distributions should first point to the latest Node.js 10 package and then install via the apt-get command from the shell:

curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
sudo apt-get install nodejs

If you decide to go with an installer available for macOS or Windows...

Now that we have npm installed, let's make use of it and install some of the modules we will be using heavily throughout this book. The most important among them is the Express framework (http://www.expressjs.com/). It is a flexible web application framework for Node.js, providing a robust RESTful API for developing single or multi-page web applications. The following command will download the Express module from the npm repository and make it available for our local Node.js installation:

npm install -g express 

You will find the express module among the results of an npm ls after a successful installation. Later in this chapter, we will learn how to write unit tests for our Node.js modules. We will need the nodeunit module for that purpose:

npm install nodeunit -g 

The -g option will install nodeunit globally....

JavaScript developers are rarely used to developing their projects in an IDE; most of them use text editors and tend to be prejudiced against anything that contradicts their views. GitHub has finally managed to calm most of them down by releasing the Atom IDE for the desktop environment. This may not solve all of the arguments about which is the best environment, but will at least bring some peace, and let people concentrate on their code, not on the tooling, which in the end is a matter of personal preference. The samples in this book are developed in the Atom IDE, but feel free to use any piece of software that can create files, including command-line editors such as vi or vim, if that would make you feel like a JS superhero, though bear in mind that superheroes are so 20^th century!

You can download the Atom IDE from https://ide.atom.io/...

Currently, our server application will behave in the same way, no matter what kind of HTTP request is processed. Let's extend it in such a way that it behaves more like an HTTP server, and start differentiating the incoming requests based on their type, by implementing handler functions for each type of request.

Let's create a new hello-node-http-server.js as follows:

var http = require('http');
var port = 8180;

function handleGetRequest(response) {
  response.writeHead(200, {'Content-Type' : 'text/plain'});
  response.end('Get action was requested');
}

function handlePostRequest(response) {
  response.writeHead(200, {'Content-Type' : 'text/plain'});
  response.end('Post action was requested');
}

function handlePutRequest(response) {
  response.writeHead(200, {'Content-Type&apos...

What we have developed so far is a simple HTTP server application that listens and processes known request types; however, it is not so well structured, as the functions handling the requests are not reusable. Node.js supports modules embracing code isolation and reusability.

We will rework our HTTP server application in such a way that the entire request handling functionality will be wrapped in a module. The module will export only a generic handler function that will take a request object as argument and, based on its request type, it will delegate the handling to inner functions not visible outside the module.

Let's start by creating a new module directory...

Now we will extend our project by providing a unit test for the HTTP module, but before diving into that, let's have a look at how Node.js supports unit testing in general. At the beginning of this chapter, we installed the Nodeunit module. Well, it's about time we started playing around with it.

First, let's create another simple Node.js module that we will use to implement our first unit test. Then we will move to more advanced topics, such as mocking JavaScript objects and using them to create unit tests for our HTTP module.

I have chosen to develop a simple math module that exports functions for adding and subtracting integer numbers, as it is straightforward enough and the results of each operation are strictly defined.

Let's start with the module and create the following math.js file in our module directory:

exports.add = function...

Node.js has an event-driven, non-blocking I/O model, which makes it perfect for real-time applications that scale well in distributed environments, such as public or private cloud platforms. Each cloud platform offers tools that allow seamless deployment, distribution, and scaling of its hosted applications. In this section, we will look at two publicly available Node.js application cloud providers—Nodejitsu and Microsoft Azure.

But first, let's spend some time on the clustering support, as it is fundamental for understanding why Node.js fits so well into the cloud environment. Node.js comes with clustering support built in to its core. Using the cluster module in your applications allows them to start as many workers as necessary to handle the load they will face. Generally, it is recommended to match the number of workers to the number of...