The Node.js Handbook, 2025 edition

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The Node.js Handbook has been one of the first books I wrote back in 2018.

It’s been downloaded tens of thousands of times, and it’s even been the base for the official Node.js documentation, something I’m quite proud of.

I’ve now completely rewritten it for 2025, focusing on what matters most for beginners learning Node.js. After feedback and careful consideration, I’ve streamlined the content to be truly beginner-friendly, removing complex production patterns in favor of clear explanations and practical examples.

This new edition focuses on fundamental concepts with explanations that help you understand not just how to use Node.js, but why things work the way they do.

This handbook provides comprehensive coverage of Node.js v22 LTS, from basic concepts to advanced topics. It includes:

40+ major topics covering all aspects of Node.js development
Modern JavaScript features and ES modules
Built-in APIs and their practical usage
Best practices for production applications
Performance considerations and optimization
Security guidelines and error handling
Real-world examples with working code

The handbook is designed for developers who want to build server-side applications with JavaScript, offering both foundational knowledge and advanced techniques for production-ready Node.js applications.

Download it from https://flaviocopes.com/access/

Here’s the full table of contents:

Introduction & Setup

Introduction to Node.js
- JavaScript runtime environment
- V8 engine outside the browser
- Single-process architecture
- Non-blocking I/O model
- Event-driven programming
- Node.js v22 LTS features
Installation
- Official packages
- Package managers (Homebrew, etc.)
- Node Version Manager (nvm)
- LTS vs Current versions
Example Application
- Basic HTTP server
- ES modules syntax
- Request/response handling
- Server configuration

Core Concepts

Node vs Browser
- Environment differences
- DOM vs Server APIs
- Module systems comparison
- ES2015+ feature support
- Environment control advantages
Running Scripts
- Command line execution
- Shebang usage
- Executable permissions
- Script configuration
Development Tools
- Built-in —watch mode
- Auto-restart functionality
- nodemon (legacy approach)

Environment & Configuration

Environment Variables
- process.env object
- Setting variables
- Built-in .env file support (v20.6+)
- dotenv package (legacy)
- Multiple .env files
Command Line Arguments
- process.argv array
- Argument parsing
- Built-in parseArgs utility (v18.3+)
- Third-party libraries
Console Output
- console.log() and methods
- Format specifiers
- Object rendering
- String formatting
User Input
- readline module
- Promise-based interface
- Interactive prompts
- Stream processing

Module System

ES Modules
- import/export syntax
- Default exports
- Named exports
- Module resolution
- node: prefix for built-ins
Top-level Await
- Async module loading
- Promise handling
- Module initialization

Event System

Event Emitter
- EventEmitter class
- Event-driven architecture
- Custom events
- Event handling patterns
Events Module API
- addListener/on methods
- emit method
- once listeners
- removeListener/off
- Event names and counts
- Listener management

File System Operations

File Descriptors
- Opening files
- File handles
- Resource management
File Information
- fs.stat() method
- File metadata
- File types and permissions
- Size and timestamps
File Paths
- Path manipulation
- Cross-platform compatibility
- Absolute vs relative paths
- Path parsing and formatting
Reading Files
- Synchronous reading
- Asynchronous reading
- Promise-based APIs
- Stream reading
Writing Files
- Write operations
- Append mode
- Stream writing
- File creation
Working with Folders
- Directory operations
- Creating folders
- Reading directory contents
- Renaming and removing
- Recursive operations

Core Modules

fs Module
- File system operations
- Synchronous methods
- Asynchronous methods
- Promise-based API
- File watching
path Module
- basename() - file names
- dirname() - directory paths
- extname() - file extensions
- join() - path concatenation
- resolve() - absolute paths
- parse() - path components
- format() - path construction
- normalize() - path cleanup
- relative() - relative paths
os Module
- arch() - system architecture
- cpus() - CPU information
- freemem() - available memory
- homedir() - home directory
- hostname() - system name
- loadavg() - system load
- networkInterfaces() - network info
- platform() - OS platform
- release() - OS version
- tmpdir() - temp directory
- totalmem() - total memory
- type() - OS type
- uptime() - system uptime
- userInfo() - user details
http Module
- HTTP server creation
- Request handling
- Response methods
- Status codes
- Headers management
- HTTP methods
- Agent configuration
- Server classes

Streams & Data Flow

Node.js Streams
- Stream fundamentals
- Why use streams
- Memory efficiency
- Composability
Stream Types
- Readable streams
- Writable streams
- Duplex streams
- Transform streams
Stream Operations
- pipe() method
- Stream chaining
- Data events
- Error handling
- Backpressure
Creating Streams
- Custom readable streams
- Custom writable streams
- Transform stream creation
- Stream implementation

Cryptography

Web Crypto API
- Cryptographic operations
- Hashing functions
- Encryption/decryption
- Key generation
- Digital signatures

Development Practices

Development vs Production
- Environment differences
- Configuration management
- Performance considerations
- Security practices
- Debugging tools
Error Handling
- Exception creation
- Error objects
- Try/catch blocks
- Uncaught exceptions
- Promise rejections
- Async/await errors
Testing
- Built-in test runner
- Test organization
- Assertions
- Test coverage
- Mocking

Network Programming

HTTP Server
- Server creation
- Request processing
- Response handling
- Routing basics
- Middleware concepts
HTTP Requests
- GET requests
- POST requests
- PUT/DELETE methods
- Request options
- Response handling
Request Body Data
- Body parsing
- JSON handling
- Form data
- File uploads
- Stream processing

Advanced Concepts

Event Loop
- Event loop phases
- Call stack
- Task queuing
- Microtasks
- Blocking operations
Asynchronous Patterns
- Callbacks
- Promises
- Async/await
- Error propagation
Timers
- setTimeout()
- setInterval()
- setImmediate()
- Recursive timers
- Timer cancellation
Process Control
- process.nextTick()
- Queue prioritization
- Event loop interaction
- Scheduling
Worker Threads
- Multi-threading in Node
- Worker creation
- Thread communication
- SharedArrayBuffer
- Use cases