Mastering Node.js: A Comprehensive Tutorial Series - Part Two - Node Modules

Overview of Node.js Modules

Node.js modules are crucial for building scalable and maintainable applications. They help organize code and extend functionality through encapsulation, scalability, and ease of maintenance. Here’s a quick guide on using different types of Node.js modules:

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Creating a Custom Module

Example: Arithmetic Operations

1. Create arithmetic.js:

   // Define basic arithmetic functions
   const add = (a, b) => a + b;
   const subtract = (a, b) => a - b;
   const multiply = (a, b) => a * b;
   const divide = (a, b) => b !== 0 ? a / b : throw new Error("Cannot divide by zero.");

   // Export functions
   module.exports = { add, subtract, multiply, divide };

1. Use in app.js:

   const arithmetic = require('./arithmetic');

   console.log(arithmetic.add(5, 3));  // Output: 8
   console.log(arithmetic.multiply(5, 3));  // Output: 15

Working with Core Modules

Commonly Used Core Modules:

• fs Module (File System): Read files asynchronously.

  const fs = require('fs');
  fs.readFile('example.txt', 'utf8', (err, data) => {
    if (err) throw err;
    console.log("File content:", data);
  });

• http Module (HTTP Server and Client): Create a server.

  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/'));

Using Third-Party Modules

Example: Express Framework

1. Install Express:

   npm install express

1. Setup Express Server:

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

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

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

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Conclusion

Node.js modules streamline the development process by organizing code into manageable sections, promoting reusability, and leveraging both the core capabilities of Node.js and the vast ecosystem of third-party modules. Understanding and using these modules efficiently is key to building robust applications.