Introduction to Node.js | Lecture 1

 

Here’s a concise set of notes introducing Node.js:

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Introduction to Node.js

What is Node.js?

• Node.js is an open-source, cross-platform runtime environment for executing JavaScript code outside a web browser.
• Built on the Google Chrome V8 JavaScript engine.
• Enables building scalable and high-performance server-side and networking applications.

Key Features:

1. Event-Driven and Non-Blocking I/O Model:
• Node.js operates asynchronously, making it efficient and lightweight for handling multiple concurrent connections.
2. Single-Threaded but Scalable:
• Uses a single thread for event handling but supports a large number of concurrent connections through the event loop.
3. Cross-Platform:
• Runs on major operating systems, including Windows, macOS, and Linux.
4. Fast Performance:
• Uses the V8 engine, which compiles JavaScript into native machine code for speed.

Core Components of Node.js:

1. Modules:
• Prebuilt or custom JavaScript code that can be imported and used in a Node.js application.
• Common Modules:
• fs (File System)
• http (HTTP server)
• path (Path utilities)
• os (Operating System utilities)
2. npm (Node Package Manager):
• Facilitates package installation, version management, and dependency management.
• Example: npm install express installs the Express.js framework.
3. Event Loop:
• Handles all asynchronous operations in Node.js, such as I/O operations, timers, and callbacks.
4. Callbacks and Promises:
• Callbacks: Functions executed after a task completes.
• Promises: A modern alternative for handling asynchronous code.

Applications of Node.js:

• Real-time chat applications
• RESTful APIs
• Single-page applications
• Streaming applications
• Microservices

Basic Example:

// Load the HTTP module

const http = require('http');

 

// Create an HTTP server

const server = http.createServer((req, res) => {

  res.statusCode = 200;

  res.setHeader('Content-Type', 'text/plain');

  res.end('Hello, World!');

});

 

// Listen on port 3000

server.listen(3000, () => {

  console.log('Server running at http://localhost:3000/');

});

Advantages of Node.js:

1. High performance for real-time applications.
2. Large and active community.
3. Same language (JavaScript) for both client-side and server-side.
4. Rich ecosystem with thousands of npm packages.

Disadvantages of Node.js:

1. Single-threaded nature can limit CPU-intensive tasks.
2. Callback hell if not managed well.
3. Lack of strong type-checking (solvable with TypeScript).

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Let me know if you need detailed examples or want to dive deeper into any specific feature!