JavaScript Node.js Standard Library: Complete Overview |…

JavaScript (Node.js) Standard Library: Complete Overview

Node.js is a JavaScript runtime built on Google's V8 engine. One of its main advantages is its rich standard library, which provides ready-made modules for solving a wide variety of tasks: from working with the file system to creating HTTP servers. In this article, we will take a detailed look at the key modules of the Node.js standard library, show examples of their use, and explain when to use which module.

1. The `fs` Module (File System)

The fs module allows you to work with the file system: read, write, delete files and directories, as well as track changes. It provides both synchronous and asynchronous methods.

const fs = require('fs');

// Asynchronous file readingfs.readFile('example.txt', 'utf8', (err, data) => {  if (err) throw err;  console.log(data);});

// Synchronous file writingfs.writeFileSync('output.txt', 'Hello, Node.js!');

fs.readFile() — asynchronous file reading.
fs.writeFileSync() — synchronous data writing to a file.
fs.mkdir() — creating a directory.
fs.unlink() — deleting a file.

2. The `path` Module

The path module provides utilities for working with file and directory paths. It automatically handles differences between operating systems (Windows, Linux, macOS).

const path = require('path');

const filePath = '/home/user/docs/file.txt';console.log(path.dirname(filePath));    // /home/user/docsconsole.log(path.basename(filePath));   // file.txtconsole.log(path.extname(filePath));    // .txt

path.join() — joins path segments.
path.resolve() — resolves a relative path to an absolute path.
path.normalize() — normalizes a path (removes extra .. and .).

3. The `http` Module

The http module allows you to create HTTP servers and clients. It is the foundation for building web applications and APIs.

const http = require('http');

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

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

http.createServer() — creates a server instance.
http.request() — makes an HTTP request to an external resource.
http.get() — a simplified version of request() for GET requests.

4. The `events` Module

The events module implements the Observer pattern. It allows you to create custom events and subscribe to them. Most Node.js objects (e.g., streams, servers) inherit from EventEmitter.

const EventEmitter = require('events');

class MyEmitter extends EventEmitter {}

const myEmitter = new MyEmitter();myEmitter.on('event', () => {  console.log('An event occurred!');});myEmitter.emit('event');