Here, we will build on the introduction to Node from the previous topic and concretize our knowledge about Node by completing exercises and activities that will help us understand how application development with Node.js is achieved. To get started with Node, the first step is installation. You have two installation options: the LTS or stable version:
LTS (Long-Term Support): Support and maintenance are provided by the Node Foundation for at least 18 months from the date of release. So, it's better to use this version for the production of backend Node applications.
Stable: Stable has support for approximately 8 months after release, with features/updates released more often. This version can be used for production if you're using Node for frontend services (dependency management). If apps can be easily updated without interrupting the environment, this version will work for backend services in Node as well. In this book, we will be using the LTS version.
Before we start with Node application development, we need to understand the built-in modules that make up Node. The set of modules that you can use without any further installation are listed as follows, along with a short description:
Assert: This module provides a set of assertion tests
Buffer: This module is used to handle binary data
Child process: This module is used to run a child process
Cluster: This module is used to handle unhandled errors
Events: This module is used to handle events
Filesystem (fs): This module is used to handle the filesystem
HTTPS: This module is used to render Node as an HTTPS server
Path: This module is used to handle file paths
Readline: This module is used to handle readable streams one line at a time
Stream: This module is used to handle streaming data
String: This module is a decoder that's used to decode buffer objects into strings
Timers: This module is used to execute a function after a given number of milliseconds
Beginning a Node application involves the following steps:
Importing and loading the required modules by invoking the require directive.
Creating the server that will receive the client's requests.
Reading the requests and returning the responses from the server that was created in the preceding step.
We will apply all of these steps in our first exercise.
Before beginning this exercise, make sure you have Node installed. Our aim is to create a Node program that will print Hello World on the browser window once the appropriate command is passed on to the server. To do so, the following steps have to be performed:
Note
The code files for this exercise can be found here: http://bit.ly/2TaT32E.
Create a JavaScript file and name it hello.js. This can be done using the options in the File tab.
Load the built-in http module by using the "require" directive and passing a constant variable (http) to it:
const http = require ('http');Declare and initialize the hostname and port as constant variables using the following code:
const hostname = '127.0.0.1'; const port = 8000;
Create the server using the createServer method and pass req and res, which denote a request to and a response from the server, respectively:
const server = http.createServer((req, res) => { res.statusCode = 200; res.setHeader('Content-Type', 'text/plain'); res.end('Hello World\n'); });This created server sends the following response to the browser:
statusCode: 200, the Content-Type header in plain text, and a string, Hello World.
Have the server listen to localhost on port 8000 using the following command:
server.listen(port, hostname, () => { console.log ('Server running at http://${hostname}:${port}/'); });Run the server using the following command prompt, as shown in the following screenshot:
node hello.js
Figure 1.3: Running the server using the command prompt
The output is as follows:
Figure 1.4: Output of the hello.js program
One of the learning objectives of this book is to create the components of a blogging application with basic features. We will commence its development in this chapter. Most of this will be done in the activity section of each topic.
You have been tasked with developing the HTTP server component for a blogging application. Your aim is to call the server and listen to the localhost on a specified port. Before you begin this activity, ensure that you have completed the previous exercise, in addition to creating a project directory named Blogging Application and a subfolder named Server. You can use an IDE of your choice; however, in this book, we are using Visual Studio.
To complete this activity, the following steps have to be completed:
Note
The code files for this activity can be found here: http://bit.ly/2TZYqz5.
Create a server.js file.
Declare and assign the HTTP server.
Declare and assign localhost and port number.
Create an HTTP server.
Listen to the server.
Run the server.js file on the command-line terminal.
Go to your browser and type in the localhost:8000 address.