Node.jsIntroduction
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.
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 usesasynchronous (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
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!)');
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
http.createServer((req, res) => {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello World!');
}).listen(8080);
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 thenode 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.js Versions & LTS:
Node.js releases a new major version every six months.
For stability, use anLTS (Long Term Support) version for production projects.
