This tutorial is designed for software programmers who want to learn the basics of Node.js and its architectural concepts. This tutorial will give you enough understanding on all the necessary components of Node.js with suitable examples.
Following are some of the important features that make Node.js the first choice of software architects.
Asynchronous and Event Driven − All APIs of Node.js library are asynchronous, that is, non-blocking. It essentially means a Node.js based server never waits for an API to return data. The server moves to the next API after calling it and a notification mechanism of Events of Node.js helps the server to get a response from the previous API call.
Single Threaded but Highly Scalable − Node.js uses a single threaded model with event looping. Event mechanism helps the server to respond in a non-blocking way and makes the server highly scalable as opposed to traditional servers which create limited threads to handle requests. Node.js uses a single threaded program and the same program can provide service to a much larger number of requests than traditional servers like Apache HTTP Server.
No Buffering − Node.js applications never buffer any data. These applications simply output the data in chunks.
License − Node.js is released under the MIT license.
Following is the link on github wiki containing an exhaustive list of projects, application and companies which are using Node.js. This list includes eBay, General Electric, GoDaddy, Microsoft, PayPal, Uber, Wikipins, Yahoo!, and Yammer to name a few.
The following diagram depicts some important parts of Node.js which we will discuss in detail in the subsequent chapters.
Following are the areas where Node.js is proving itself as a perfect technology partner.
It is not advisable to use Node.js for CPU intensive applications.
You really do not need to set up your own environment to start learning Node.js. Reason is very simple, we already have set up Node.js environment online, so that you can execute all the available examples online and learn through practice. Feel free to modify any example and check the results with different options.
Try the following example using the Live Demo option available at the top right corner of the below sample code box (on our website) −/* Hello World! program in Node.js */ console .log("Hello World!");
For most of the examples given in this tutorial, you will find a Try it option, so just make use of it and enjoy your learning.
If you are still willing to set up your environment for Node.js, you need the following two softwares available on your computer, (a) Text Editor and (b) The Node.js binary installables.
This will be used to type your program. Examples of few editors include Windows Notepad, OS Edit command, Brief, Epsilon, EMACS, and vim or vi.
Name and version of text editor can vary on different operating systems. For example, Notepad will be used on Windows, and vim or vi can be used on windows as well as Linux or UNIX.
The files you create with your editor are called source files and contain program source code. The source files for Node.js programs are typically named with the extension ".js".
Before starting your programming, make sure you have one text editor in place and you have enough experience to write a computer program, save it in a file, and finally execute it.
Node.js distribution comes as a binary installable for SunOS , Linux, Mac OS X, and Windows operating systems with the 32-bit (386) and 64-bit (amd64) x86 processor architectures.
Following section guides you on how to install Node.js binary distribution on various OS.
Download latest version of Node.js installable archive file from Node.js Downloads. At the time of writing this tutorial, following are the versions available on different OS.
Based on your OS architecture, download and extract the archive node-v6.3.1-osname.tar.gz into /tmp, and then finally move extracted files into /usr/local/nodejs directory. For example:
Add /usr/local/nodejs/bin to the PATH environment variable.
Use the MSI file and follow the prompts to install the Node.js. By default, the installer uses the Node.js distribution in C:\Program Files\nodejs. The installer should set the C:\Program Files\nodejs\bin directory in window's PATH environment variable. Restart any open command prompts for the change to take effect.
Create a js file named main.js on your machine (Windows or Linux) having the following code.
Now execute main.js file using Node.js interpreter to see the result −
If everything is fine with your installation, this should produce the following result −
Before creating an actual "Hello, World!" application using Node.js, let us see the components of a Node.js application. A Node.js application consists of the following three important components −
Import required modules − We use the require directive to load Node.js modules.
Create server − A server which will listen to client's requests similar to Apache HTTP Server.
Read request and return response − The server created in an earlier step will read the HTTP request made by the client which can be a browser or a console and return the response.
We use the require directive to load the http module and store the returned HTTP instance into an http variable as follows −
We use the created http instance and call http.createServer() method to create a server instance and then we bind it at port 8081 using the listen method associated with the server instance. Pass it a function with parameters request and response. Write the sample implementation to always return "Hello World".
The above code is enough to create an HTTP server which listens, i.e., waits for a request over 8081 port on the local machine.
Let's put step 1 and 2 together in a file called main.js and start our HTTP server as shown below −
Now execute the main.js to start the server as follows −
Verify the Output. Server has started.