nodejslibaries

Here's a list of 20 popular Node.js libraries that are frequently used in development:

Here's a list of 20 libraries that are commonly used alongside Express for building APIs:

1. body-parser:

Parses incoming request bodies in a middleware before your handlers, available under the req.body property.

body-parser:

The body-parser middleware is used in Express.js applications to parse incoming request bodies before your handlers, making it easy to extract and use form data and JSON payloads.

Basic body-parser Example: Here's a simple use case for body-parser where it parses incoming JSON payloads.

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

// Middleware that parses incoming JSON requests and puts the parsed data in req.body
app.use(bodyParser.json());

app.post('/users', (req, res) => {
  console.log(req.body); // Access the parsed JSON body data
  res.send('User data received');
});

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

In this basic example, the body-parser middleware is used to parse JSON request bodies. Any POST request to /users with a JSON payload will have its body parsed, and the data will be available in req.body.

Advanced body-parser Example: For more advanced use cases, you might need to handle different types of request bodies, such as URL-encoded data or raw text.

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

// Middleware for JSON bodies
app.use(bodyParser.json());

// Middleware for URL-encoded bodies (like the ones sent by HTML forms)
app.use(bodyParser.urlencoded({ extended: true }));

// Middleware for parsing text bodies
app.use(bodyParser.text());

app.post('/users', (req, res) => {
  // req.body will be an object if JSON was sent,
  // a string if text/plain was sent,
  // or a nested object if a form was submitted.
  console.log(req.body);
  res.send('User data received');
});

// A route for text/plain body
app.post('/text', (req, res) => {
  console.log(req.body); // Access the parsed text body data
  res.send('Text received');
});

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

In the advanced example, different body-parser configurations are used to parse different content types: JSON, URL-encoded, and plain text. This allows for more flexibility in handling various types of POST requests. The extended: true option allows for rich objects and arrays to be URL-encoded, giving you the ability to parse data sent from HTML form elements.

2. cors:

Enables CORS (Cross-Origin Resource Sharing), allowing you to configure the various options that dictate which resources can be requested from a web page in another domain.

cors:

CORS, or Cross-Origin Resource Sharing, is a security feature that allows or restricts resources on a web page to be requested from another domain. By default, web browsers restrict web pages from making requests to a different domain than the one that served the web page, which is known as the same-origin policy. The cors package for Node.js is a middleware that can enable and configure CORS in your Express application.

Basic Example:

For a simple setup where you want to allow requests from any origin, you can use the cors middleware without any configuration.

Here's a basic example of enabling CORS for all routes and origins:

• Install the cors package and its TypeScript definitions.
• Import cors into your Express application.
• Use cors as middleware without any options to allow all cross-origin requests.

import express from 'express';
import cors from 'cors';

const app = express();

// Enable CORS for all routes and origins
app.use(cors());

app.get('/data', (req, res) => {
  res.json({ message: 'This route is CORS-enabled for all origins!' });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000 with basic CORS enabled.');
});

Advanced Example:

In a real-world application, you may need to configure CORS more granularly, specifying which origins are allowed, which HTTP methods are permitted, and whether credentials are supported.

Here's a more advanced setup with specific CORS options:

• Configure CORS to allow specific origins and methods.
• Enable pre-flight requests for complex methods.
• Include credentials in the CORS configuration.

import express from 'express';
import cors from 'cors';

const app = express();

const corsOptions: cors.CorsOptions = {
  origin: ['https://example.com', 'https://api.example.com'], // Specify allowed origins
  methods: ['GET', 'POST', 'PUT', 'DELETE'], // Specify allowed methods
  allowedHeaders: ['Content-Type', 'Authorization'], // Specify allowed headers
  credentials: true, // Enable credentials
  optionsSuccessStatus: 200, // For legacy browsers
};

// Enable CORS with the specified options
app.use(cors(corsOptions));

// Enable pre-flight requests for all routes
app.options('*', cors(corsOptions));

app.get('/data', (req, res) => {
  res.json({ message: 'This route is CORS-enabled with specific options.' });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000 with advanced CORS configuration.');
});

In the advanced example:

• A corsOptions object is defined to set up the CORS policy.
• The origin property specifies which domains are allowed to access your resources.
• The methods property lists the HTTP methods allowed when accessing the resource.
• The credentials property is set to true to allow cookies and authorization headers to be included in cross-origin requests.
• The app.options('*', cors(corsOptions)); line sets up the response for pre-flight requests, which are sent by browsers for HTTP requests that involve some risk, such as DELETE, PUT, or when using custom headers.

3. morgan:

HTTP request logger middleware that simplifies the process of logging requests to your application.

morgan:

Morgan is an HTTP request logger middleware for Node.js that simplifies the process of logging requests that come into your application. It's particularly useful for developing and debugging.

Basic Morgan Usage Example Code Explanation:

import express from 'express';
import morgan from 'morgan';

// Create an Express application
const app = express();

// Use morgan with the 'dev' format which is a predefined format for concise colored output
app.use(morgan('dev'));

// Define a simple GET route
app.get('/', (req, res) => {
  res.send('Hello, World!');
});

// Start the server
app.listen(3000, () => {
  console.log('Server listening on port 3000');
});

In the basic example:

• We import and use Morgan with the 'dev' format. This format outputs colored response status codes for easy reading during development.
• Every request made to the server is logged to the console with details like the HTTP method, path, response status, and response time.

Advanced Morgan Usage with Custom Token and Format Example Code Explanation:

import express from 'express';
import morgan from 'morgan';
import fs from 'fs';
import path from 'path';

const app = express();

// Create a write stream (in append mode) for logging to a file
const accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), { flags: 'a' });

// Setup custom token to log the user agent
morgan.token('agent', (req, res) => req.headers['user-agent']);

// Use morgan with a custom format that includes our custom token
app.use(morgan(':method :url :status :response-time ms - :agent', { stream: accessLogStream }));

// Define a simple GET route
app.get('/', (req, res) => {
  res.send('Hello, World!');
});

// Start the server
app.listen(3000, () => {
  console.log('Server listening on port 3000');
});

In the advanced example:

• We create a custom token named 'agent' to log the user agent from the request headers.
• We define a custom logging format that includes the HTTP method, URL, status code, response time, and the user agent.
• Instead of logging to the console, we log all requests to a file named access.log using a write stream.
• This setup allows for more complex logging requirements and is suitable for production environments where logs need to be persisted and analyzed later.

4. helmet:

Helps secure your Express apps by setting various HTTP headers to prevent attacks like Cross-Site-Scripting (XSS), clickjacking, etc.

Certainly! I will explain the key points of using Helmet in a TypeScript Express application with code examples for each security feature it provides.

Helmet in Express Applications:

Helmet helps to secure your Express apps by automatically setting HTTP headers that are crucial for protecting against various web vulnerabilities.

XSS Protection: Helmet sets the X-Content-Type-Options header to nosniff, which helps prevent browsers from trying to guess ("sniff") the MIME type, which can have security implications.

import helmet from 'helmet';
import express from 'express';

const app = express();

app.use(helmet.xssFilter());

Hide Powered-By: Helmet can remove the X-Powered-By header to make it less obvious what server technology you are using, thus obscuring the stack from potential attackers.

app.use(helmet.hidePoweredBy());

HTTP Strict Transport Security (HSTS): This tells browsers to stick with HTTPS and never visit the unsecured HTTP version of your site.

app.use(helmet.hsts({
  maxAge: 31536000, // 1 year in seconds
  includeSubDomains: true, // Must be enabled for preloading
  preload: true
}));

Disable Content Sniffing: This setting prevents the browser from trying to guess the content type of files.

app.use(helmet.noSniff());

Frame Options: To protect against clickjacking, Helmet can set the X-Frame-Options header to tell the browser to prevent your webpage from being put in a frame or iframe.

app.use(helmet.frameguard({ action: 'deny' }));

DNS Prefetch Control: This controls browser DNS prefetching, which can improve user privacy at the expense of performance.

app.use(helmet.dnsPrefetchControl({ allow: false }));

IE No Open: Sets the X-Download-Options header to prevent Internet Explorer from executing downloads in your site’s context.

app.use(helmet.ieNoOpen());

Referrer Policy: This sets the Referrer-Policy header to control what information is sent along with the requests.

app.use(helmet.referrerPolicy({ policy: 'no-referrer' }));

Content Security Policy (CSP): Helmet can help set a Content Security Policy to control which resources the user agents are allowed to load for a given page.

app.use(helmet.contentSecurityPolicy({
  directives: {
    defaultSrc: ["'self'"],
    scriptSrc: ["'self'", "'unsafe-inline'"],
    objectSrc: ["'none'"],
    upgradeInsecureRequests: [],
  }
}));

By including these Helmet settings in your Express application, you enhance its security by setting strict rules on how your app is accessed and interacted with, making it less vulnerable to common web attacks.

5. passport:

Authentication middleware that is extremely flexible and modular, can be dropped into any Express-based web application. A variety of strategies support authentication using a username and password, Facebook, Twitter, and more.

6. multer:

Middleware for handling multipart/form-data, which is primarily used for uploading files.

7. cookie-parser:

Parse Cookie header and populate req.cookies with an object keyed by cookie names.

8. express-validator:

Middleware that wraps validator.js, a library that provides validator and sanitizer functions, for validation and sanitization of request data.

9. compression:

Middleware that compresses response bodies for all requests that traverse through the middleware.

10. express-session:

Simple session middleware for Express, providing the ability to implement session functionality.

11. connect-redis:

Provides Redis session storage for Express, used in conjunction with express-session.

12. errorhandler:

Middleware for handling errors during development. It provides stack traces and error message responses for HTTP requests.

13. method-override:

Lets you use HTTP verbs like PUT or DELETE in places where the client doesn't support it.

14. response-time:

Middleware that records the response time for HTTP requests in Express.

15. serve-favicon:

Middleware for serving a favicon, caching the icon in memory to improve performance for subsequent requests.

16. express-rate-limit:

Middleware to limit repeated requests to public APIs and/or endpoints such as password reset.

17. express-jwt:

Middleware that validates JSON Web Tokens and sets req.user.

18. winston:

A multi-transport async logging library for Node.js, used for logging error and information messages.

19. joi:

Object schema description language and validator for JavaScript objects that allows you to create blueprints or schemas for JavaScript objects to ensure validation of key information.

20. celebrate:

An express middleware function that wraps the joi validation library and adds a bit of sugar to make it easier to validate requests.

These libraries cover a wide range of functionalities needed for robust API development with Express, including logging, security, file uploads, data validation, and error handling.

1. express:

Express is a fast, unopinionated, minimalist web framework for Node.js, widely used to build APIs and web applications. It simplifies routing, middleware integration, and many other web server features.

2. lodash:

Lodash is a modern JavaScript utility library delivering modularity, performance, & extras. It makes JavaScript easier by taking the hassle out of working with arrays, numbers, objects, strings, etc.

3. async:

Async is a utility module that provides straightforward, powerful functions for working with asynchronous JavaScript, such as asynchronous loops, parallel execution, and control flow.

4. moment:

Moment.js is a library for parsing, validating, manipulating, and formatting dates. It's been a staple for JavaScript developers dealing with date and time operations, despite being in maintenance mode.

5. mongoose:

Mongoose is an Object Data Modeling (ODM) library for MongoDB and Node.js. It manages relationships between data, provides schema validation, and is used to translate between objects in code and their representation in MongoDB.

6. socket.io:

Socket.IO enables real-time, bidirectional, and event-based communication between web clients and servers. It's widely used for chatting applications, real-time analytics, and binary streaming.

7. axios:

Axios is a promise-based HTTP client for the browser and Node.js, often used to send asynchronous HTTP requests to REST endpoints.

8. chalk:

Chalk is a library that allows you to style your Node.js console logs with colors and styles, which is helpful for making log output more readable.

9. bluebird:

Bluebird is a fully-featured Promise library with a focus on innovative features and performance. It provides a robust toolset for working with Promises in asynchronous operations.

10. body-parser:

Body-parser is a middleware that parses incoming request bodies in a middleware before your handlers, available under the req.body property.

11. passport:

Passport is authentication middleware for Node.js. Extremely flexible and modular, Passport can be unobtrusively dropped into any Express-based web application to provide authentication mechanisms.

12. dotenv:

Dotenv is a zero-dependency module that loads environment variables from a .env file into process.env, which is useful for managing configuration settings.

13. cors:

The cors library is middleware that can be used to enable Cross-Origin Resource Sharing (CORS) with various options. It's essential for setting up a web server that needs to accept cross-domain requests.

14. redis:

Node Redis is the official Node.js client for Redis, a high-performance in-memory key-value database, which is frequently used for caching in Node.js applications.

15. nodemon:

Nodemon is a utility that monitors for any changes in your source and automatically restarts your server, perfect for development.

16. pg:

Also known as node-postgres, this is a collection of Node.js modules for interfacing with your PostgreSQL database. It provides solid, native integration with PostgreSQL.

17. commander:

Commander.js is the complete solution for node.js command-line interfaces, inspired by Ruby's commander.

18. sequelize:

Sequelize is a promise-based Node.js ORM for Postgres, MySQL, MariaDB, SQLite, and Microsoft SQL Server. It features solid transaction support, relations, eager and lazy loading, read replication, and more.

19. cheerio:

Cheerio uses jQuery-like syntax to manipulate, traverse, and render HTML on the server, which is useful for web scraping or server-side DOM manipulation.

20. jest:

Jest is a delightful JavaScript testing framework with a focus on simplicity. It works well with projects using Babel, TypeScript, Node.js, React, Angular, Vue, and more.

These libraries are central to many Node.js projects, addressing various aspects like HTTP requests, data handling, and workflow automation. Knowing these will be beneficial not only for interviews but also for practical development.