JavaScript Node.js Standard Library: A Complete Overview |…

Standard JavaScript Library (Node.js): Complete Overview

Node.js is a JavaScript runtime environment built on Google's V8 engine. Unlike browser JavaScript, Node.js offers a powerful built-in standard library that allows you to work with the file system, network, data streams, cryptography, and much more. In this article, we will take a detailed look at the key modules of the Node.js standard library that every developer needs.

1. Module `fs` (File System)

The fs module provides an API for interacting with the file system. It supports both synchronous and asynchronous operations.

Reading a file:

const fs = require('fs');

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

// Synchronous readingconst data = fs.readFileSync('example.txt', 'utf8');console.log(data);

Writing to a file:

const fs = require('fs');

fs.writeFile('output.txt', 'Hello, world!', (err) => {    if (err) throw err;    console.log('File saved');});

The module also supports working with directories, streams, and access permissions.

2. Module `path` (Working with paths)

The path module simplifies manipulations with file paths and ensures cross-platform compatibility.

const path = require('path');

const fullPath = '/users/docs/file.txt';console.log(path.dirname(fullPath));    // /users/docsconsole.log(path.basename(fullPath));   // file.txtconsole.log(path.extname(fullPath));    // .txt

// Path constructionconst newPath = path.join('/users', 'docs', 'file.txt');console.log(newPath); // /users/docs/file.txt

3. Module `http` (HTTP server and client)

With http, you can create web servers and send HTTP requests without third-party libraries.

Simple HTTP server:

const http = require('http');

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

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

HTTP request (client):

const http = require('http');

http.get('http://api.example.com/data', (res) => {    let data = '';    res.on('data', chunk => data += chunk);    res.on('end', () => console.log(data));});

4. Module `stream` (Data streams)

Streams allow you to process large volumes of data in chunks without loading everything into memory. Node.js supports four types of streams: Readable, Writable, Duplex, and Transform.

const fs = require('fs');const zlib = require('zlib');

// Reading from a file, compressing, and writingconst readStream = fs.createReadStream('input.txt');const writeStream = fs.createWriteStream('output.txt.gz');const gzip = zlib.createGzip();

readStream.pipe(gzip).pipe(writeStream);

5. Module `crypto` (Cryptography)

The crypto module provides functionality for hashing, encryption, and random number generation.

const crypto = require('crypto');

// Password hashingconst hash = crypto.createHash('sha256').update('myPassword123').digest('hex');console.log(hash);

// Generating random bytescrypto.randomBytes(16, (err, buffer) => {    console.log(buffer.toString('hex'));});