Node.js is a free, open source tool that lets you run JavaScript outside the web browser.
With Node.js, you can build fast and scalable applications like web servers, APIs, tools, and more.
What Can You Build With Node.js?
Node.js uses an event-driven, non-blocking model.
It can handle many connections at once without waiting for one to finish before starting another.
This makes it great for real-time apps and high-traffic websites.
Here are some examples of what you can build with Node.js:
- Web servers and websites
- REST APIs
- Real-time apps (like chat)
- Command-line tools
- Working with files and databases
- IoT and hardware control
How to Run Node.js Code
Save your code in a file, for example app.js, then run it in your terminal or command prompt with:
node app.js
This will start your Node.js program.
Learning by Examples
Our "Show Node.js" tool makes it easy to learn Node.js, it shows both the code and the result.
Example
let http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World!');
}).listen(8080);
Click on the "Run example" button to see how it works.
Examples Running in the Command Line Interface
In this tutorial there will be some examples that are better explained by displaying the result in the command line interface.
When this happens, The "Show Node.js" tool will show the result in a black screen on the right:
Example
console.log('This example is different!');
console.log('The result is displayed in the Command Line Interface');
Click on the "Run example" button to see how it works.
Node.js Built-in Modules
Node.js comes with many built-in modules to help you work with files, servers, paths, the operating system, and more.
You can use them by importing them with require().
Example: Using the OS Module
const os = require('os');
console.log(os.platform());
See the full list of built-in modules.
What is npm?
npm is the package manager for Node.js.
It helps you install and manage third-party packages (libraries) to add more features to your apps.
Example: Installing a Package
npm install express
This command installs the popular Express web framework.
You can then use it in your code:
const express = require('express');
const app = express();
app.get('/', (req, res) => res.send('Hello World!'));
app.listen(8080);
Download Node.js
Download Node.js from the official Node.js web site: https://nodejs.org
Node.js Exercises
Many chapters in this tutorial end with an exercise where you can check your level of knowledge.
Node.js Quiz
Test your Node.js skills with a quiz.
