Node.js Guide

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Why Use Node.js?

• JavaScript Everywhere: Use the same language for frontend and backend
• Fast Performance: Non-blocking I/O and event-driven architecture
• Rich Ecosystem: Access to millions of packages via npm
• Active Community: Large, supportive developer community
• Scalability: Built for handling concurrent connections efficiently

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Installing Node.js

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Choosing Your Installation Method

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apt Installation

• Quick setup and getting started
• Production servers with a single Node.js version
• Simple projects that don’t need version switching

• Fast and straightforward
• Managed by system package manager
• Good for beginners

• Limited to one Node.js version
• May not have the latest version
• Harder to switch versions

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nvm Installation

• Development environments
• Working on multiple projects with different Node.js versions
• Testing across different Node.js versions
• Projects requiring specific Node.js versions

• Install multiple Node.js versions
• Easy version switching
• Always access to latest versions
• Per-project version configuration

• Slightly more complex setup
• Additional tool to manage
• Version specific to user account

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Getting Started with Node.js

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Your First Node.js Application

// hello.js
console.log('Hello, Node.js!');

node hello.js

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Creating a Web Server

// server.js
const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello World\n');
});

server.listen(3000, () => {
  console.log('Server running at http://localhost:3000/');
});

node server.js

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Working with npm

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Initializing a Project

# Create package.json interactively
npm init

# Create package.json with defaults
npm init -y

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Managing Packages

# Install a package
npm install express

# Install as dev dependency
npm install --save-dev nodemon

# Install globally
npm install -g typescript

# Install specific version
npm install [email protected]

# Remove a package
npm uninstall express

# Update packages
npm update

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Using npm Scripts

{
  "scripts": {
    "start": "node server.js",
    "dev": "nodemon server.js",
    "test": "jest",
    "build": "tsc"
  }
}

npm run dev
npm start
npm test

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Managing Node.js Versions with nvm

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Common nvm Commands

# List available Node.js versions
nvm list-remote

# Install a specific version
nvm install 18.17.0

# Install latest LTS version
nvm install --lts

# Switch to a version
nvm use 18.17.0

# Set default version
nvm alias default 18.17.0

# List installed versions
nvm list

# Show current version
nvm current

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Per-Project Node.js Versions

18.17.0

# Use version from .nvmrc
nvm use

# Install version from .nvmrc
nvm install

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Building a Node.js Project

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Project Structure

my-project/
├── node_modules/     # Dependencies (git ignored)
├── src/              # Source code
│   ├── index.js      # Entry point
│   └── routes/       # Application routes
├── tests/            # Test files
├── .gitignore        # Git ignore file
├── package.json      # Project metadata
└── README.md         # Project documentation

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Essential Files

{
  "name": "my-project",
  "version": "1.0.0",
  "description": "My Node.js project",
  "main": "src/index.js",
  "scripts": {
    "start": "node src/index.js"
  },
  "dependencies": {
    "express": "^4.18.2"
  }
}

node_modules/
.env
*.log
dist/

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Popular Node.js Frameworks

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Express.js

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello Express!');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

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Other Popular Frameworks

• Nest.js: Progressive framework for building efficient server-side applications
• Fastify: Fast and low overhead web framework
• Koa: Next generation web framework by Express team
• Hapi: Rich framework for building applications and services

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Best Practices

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Security

• Keep Node.js and npm updated
• Audit dependencies regularly with npm audit
• Use environment variables for sensitive data
• Don’t commit node_modules/ or .env files
• Validate and sanitize user input

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Performance

• Use async/await for asynchronous operations
• Implement caching where appropriate
• Use clustering for CPU-intensive tasks
• Monitor memory usage and prevent leaks
• Enable compression for HTTP responses

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Development

• Use ESLint for code quality
• Implement automated testing
• Use nodemon for automatic restarts during development
• Follow semantic versioning
• Document your code and API

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Environment Variables

PORT=3000
DB_HOST=localhost
DB_USER=admin
DB_PASS=secret

require('dotenv').config();

const port = process.env.PORT || 3000;
const dbHost = process.env.DB_HOST;

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Debugging Node.js

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Console Debugging

console.log('Variable value:', myVariable);
console.error('Error occurred:', error);
console.table(arrayOfObjects);

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Using Node.js Inspector

# Start with inspector
node --inspect server.js

# Debug from the start
node --inspect-brk server.js

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Testing

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Popular Testing Frameworks

• Jest: All-in-one testing framework
• Mocha: Flexible testing framework
• Chai: Assertion library
• Supertest: HTTP assertion library

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Basic Jest Example

// math.test.js
const { add } = require('./math');

test('adds 1 + 2 to equal 3', () => {
  expect(add(1, 2)).toBe(3);
});

npm test

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Next Steps

• Building RESTful APIs
• Working with databases (MongoDB, PostgreSQL)
• Real-time applications with Socket.io
• Microservices architecture
• Serverless functions
• TypeScript for type safety

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Related Resources