🧰 Node.js File & Server Operations – Handle Files, Uploads, Emails, and HTTP with Ease

🧲 Introduction – Manage Files and Servers Like a Pro with Node.js

Node.js offers robust capabilities for file handling and server communication through built-in and third-party modules. From reading local files to building HTTP servers, sending emails, and managing file uploads—Node.js provides both low-level control and high-level simplicity.

🎯 In this guide, you’ll learn:

• How to use the fs module to read/write/delete files
• How to handle file uploads in Node.js
• How to send emails using third-party modules
• How to create HTTP servers and parse URLs

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📘 Topics Covered

🔹 Topic	📖 Description
📁 Node.js – File System Module	Use fs module to read, write, rename, and delete files and directories
⬆️ Node.js – Uploading Files	Accept and store uploaded files from HTML forms
✉️ Node.js – Sending Emails	Send emails using SMTP with nodemailer
🔗 Node.js – HTTP & URL Modules	Create web servers and parse incoming request URLs

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📁 Node.js – File System Module (fs)

Node.js provides the fs (File System) module for interacting with the local file system.

🔹 Read File Asynchronously

const fs = require('fs');

fs.readFile('demo.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

🔹 Write to a File

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

🔹 Delete a File

fs.unlink('output.txt', (err) => {
  if (err) throw err;
  console.log('File deleted!');
});

🧪 Output:

Hello Node.js!
File saved!
File deleted!

✅ The fs module supports both async and sync versions (fs.readFileSync, fs.writeFileSync).

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⬆️ Node.js – Uploading Files

To handle file uploads, you can use the formidable or multer module. Here’s a basic example with formidable.

npm install formidable

🔹 HTML Upload Form

<form action="upload" method="post" enctype="multipart/form-data">
  <input type="file" name="fileupload">
  <input type="submit">
</form>

🔹 Upload Handler (Node.js)

const http = require('http');
const formidable = require('formidable');
const fs = require('fs');

http.createServer((req, res) => {
  if (req.url === '/upload' && req.method === 'POST') {
    const form = new formidable.IncomingForm();
    form.parse(req, (err, fields, files) => {
      const oldPath = files.fileupload.filepath;
      const newPath = './uploads/' + files.fileupload.originalFilename;

      fs.rename(oldPath, newPath, () => {
        res.write('File uploaded and moved!');
        res.end();
      });
    });
  }
}).listen(3000);

🧪 Output:

File uploaded and moved!

✅ Make sure the uploads directory exists in your project.

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✉️ Node.js – Sending Emails

To send emails in Node.js, use the nodemailer module.

npm install nodemailer

🔹 Basic Email Example

const nodemailer = require('nodemailer');

let transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: 'your_email@gmail.com',
    pass: 'your_password'
  }
});

let mailOptions = {
  from: 'your_email@gmail.com',
  to: 'recipient@example.com',
  subject: 'Node.js Email Test',
  text: 'This email was sent using Node.js!'
};

transporter.sendMail(mailOptions, (error, info) => {
  if (error) throw error;
  console.log('Email sent: ' + info.response);
});

🧪 Output:

Email sent: 250 2.0.0 OK

✅ Use app-specific passwords and secure configs when deploying.

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🔗 Node.js – HTTP & URL Modules

Node.js lets you build servers and parse URLs without frameworks.

🔹 Create a Basic Server

const http = require('http');

http.createServer((req, res) => {
  res.write('Welcome to Node.js Server!');
  res.end();
}).listen(3000);

🔹 Parse URL and Query String

const url = require('url');

http.createServer((req, res) => {
  const q = url.parse(req.url, true).query;
  res.write('Hello ' + (q.name || 'Guest'));
  res.end();
}).listen(3000);

🧪 Output:

Visit: http://localhost:3000/?name=John
→ Hello John

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📌 Summary – Recap & Next Steps

Node.js simplifies file management and server operations using built-in and third-party tools. With just a few lines of code, you can read files, host web servers, upload content, and send emails—all asynchronously and efficiently.

🔍 Key Takeaways:

• fs module handles file reading/writing/deleting
• File uploads are handled using formidable or multer
• nodemailer allows SMTP-based email sending
• http and url modules build custom web servers without Express

⚙️ Real-World Uses:

• File upload APIs for cloud storage apps
• Email notifications in registration systems
• Static site file serving and templating
• Simple chat or dashboard servers

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❓ Frequently Asked Questions

❓ How do I read a file in Node.js?
✅ Use fs.readFile(filename, 'utf8', callback) to read a file asynchronously.

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❓ How to upload files to a server using Node.js?
✅ Use modules like formidable or multer to parse incoming form data and move files.

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❓ Can Node.js send emails without a server?
✅ Yes, using nodemailer, you can send SMTP emails via Gmail or another mail service.

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❓ What’s the difference between fs and http modules?
✅ fs is for file system operations; http is for creating servers and handling web requests.

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❓ How to parse URL parameters in Node.js?
✅ Use url.parse(req.url, true).query to extract query strings like ?name=John.

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