Coding a node server is much easier to do than one might imagine. Understanding how it works is another story. To help you understand the challenges you will face once your first node server is created, it is important to figure out how it works.
Whether in node, in PHP or whatever the language, an application or a website needs a server to function. This server is a computer – with greater processor power and RAM, but without a graphics card – that is plugged into a data center and constantly on. Its role is to respond to user requisitions and deliver an HTML page or files (in JSON or more rarely XML format).
Why Node.JS for the web?
Unlike PHP, Ruby on Rails or Java, a node js runs with a single thread. That is to say, it will perform one action at a time. At the same time, a node js server is never pending. If a client’s request is time-consuming, it has the ability to launch the process and move on to the next ones without waiting for it to be completed. This is called asynchronous.
Limits of a Node.js server
Where a node server is very strong to meet the needs of the majority of web applications, it is much less suitable for CPU-intensive operations. Processing large datasets or performing long calculations will be much more efficient in Python than in Node.
This is one of the reasons why large web applications are structured around microservices. For the same application, a node server will be in charge of processing HTTP requests and outsource the performance of more complex operations to other services. These can be developed in a better suitable language.
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Creating the first node js server
Before you start, make sure you have installed node.js. Look at the example of a simplest node js web server:
In this short script you have all you need to receive user requests and to respond to them.
To understand what this code accomplishes, break down the important elements: The http constant allows us to import code from the “http” module natively present in nodejs.
const http = require(“http”);
The http module is a javascript object, containing data and functions that are needed to create a web server.
In the rest of your code, use the “ createServer ” operation present in the HTTP object. This process takes a callback as a criterion, a function that is invoked when the task calling it has finished.
This callback takes 2 parameters :
- The request object ( req ) which will contain the information sent by the client such as, for example, the URL, the parameters (everything that comes after the “?” in a URL) or the browser used and its version.
- The response object ( res ) which contains the elements that the client needs to consider its request as completed successfully, or if necessary the error to communicate to the user.
In this piece of code, ask your node server to respond to each request it receives by displaying the plain text “ Hello World! ” then signal the end of the answer.
To launch and test created server on your device:
- Open your terminal, navigate to your directory
- Create a server.js file in your working directory
- Paste the codeBack on your terminal, type the command node server.js
- Open your browser and type localhost:3000to send it a request
Use a framework for a better node server
Did you manage to launch your node server locally? Well done! Only your server is useless except to answer a Hello World. That’s great for a start, but now you’ll want to add different behaviors depending on user actions, store data in the database, manage authenticated or unauthenticated user sessions.
To develop a more complex application, there is no need to do everything in pure node js. Use a framework. You can always ask for help from professionals and hire net developers if needed.
A framework is a library that will abstract the heavy lifting and make writing your server code easier. The most famous nodejs frameworks are Express, Nest, Koa among many others.
The same node server in Express.js would look like this:
Start by importing the express module. Unlike the HTTP module, Express is not included with node. You have to download this package using npm via the following command:
npm install express
The following line is used to launch express and its features that you will need to code your node web server.
const app = express()
Start by declaring the first route. When a client sends an HTTP “GET” request to the url ‘localhost:8080/’, your node server will respond “Hello World”.
Once your route has been declared, you can launch the server and ask it to listen on port 8080 .
