Node.js Introduction
What You'll Learn
In this tutorial, you'll learn:
- How to install and run Node.js
- Core concepts like modules and the event loop
- How to build web servers and APIs
- Working with databases and files
- Deploying Node.js applications
What is Node.js?
Node.js is a free, open-source JavaScript runtime that runs on Windows, Mac, Linux, and more.
It lets you execute JavaScript code outside of a web browser, enabling server-side development with JavaScript.
Built on Chrome's V8 JavaScript engine, Node.js is designed for building scalable network applications efficiently.
Example: Print a MessageGet your own Node.js Server
console.log('Hello from Node.js!');
Try it Yourself »
Why Node.js?
Node.js excels at handling many simultaneous connections with minimal overhead, making it perfect for:
- Real-time applications (chats, gaming, collaboration tools)
- APIs and microservices
- Data streaming applications
- Command-line tools
- Server-side web applications
Its non-blocking, event-driven architecture makes it highly efficient for I/O-heavy workloads.
Asynchronous Programming
Node.js uses asynchronous (non-blocking) programming.
This means it can keep working while waiting for tasks like reading files or talking to a database.
With asynchronous code, Node.js can handle many things at once—making it fast and efficient.
Example: Read a File Asynchronously
// Load the filesystem module
const fs = require('fs');
// Read file asynchronously
fs.readFile('myfile.txt', 'utf8', (err, data) => {
if (err) {
console.error('Error reading file: ' + err);
return;
}
console.log('File content: ' + data);
});
console.log('Reading file... (this runs first!)');
Run example »
In this example:
- We load the built-in
fsmodule - We call
readFileto read a file - Node.js continues to the next line while reading the file
- When the file is read, our callback function runs
This non-blocking behavior lets Node.js handle many requests efficiently.
What Can Node.js Do?
- Web Servers: Create fast, scalable network applications
- File Operations: Read, write, and manage files on the server
- Database Interaction: Work with databases like MongoDB, MySQL, and more
- APIs: Build RESTful services and GraphQL APIs
- Real-time: Handle WebSockets for live applications
- CLI Tools: Create command-line applications
Example: Simple Web Server
const http = require('http');
http.createServer((req, res) => {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World!');
}).listen(8080);
Run example »
What is a Node.js File?
Node.js files contain code that runs on the server. They usually have the .js extension and can be started with the node command.
- Node.js files run tasks when certain events happen (like a web request)
- They must be started on the server to have any effect
- They use JavaScript syntax
Example: Running a Node.js File
node app.js
Node.js Versions & LTS:
Node.js releases a new major version every six months.
For stability, use an LTS (Long Term Support) version for production projects.
