Node.js Real-time Chat Application

A modern, real-time chat application built with Node.js, Express, and Socket.IO. Features text messaging, image sharing, file transfers, and real-time user presence.

✨ Features

• Real-time Messaging: Instant text communication with other users
• Media Sharing: Send and receive images directly in chat
• File Transfers: Share files with icon-based visual indicators
• User Presence: See who's online in real-time
• Responsive Design: Works on desktop and mobile devices
• File Security: 10MB file size limit with type validation
• Modern UI: Gradient design with smooth animations

📁 Project Structure

chat-app/
├── server.js                 # Main server file
└── public/
    ├── index.html            # Frontend interface
    └── favicon.ico           # Website icon

🚀 Quick Start

Prerequisites

• Node.js (v14 or higher)
• npm or yarn

Installation & Running

1. Clone or download the project files

   Create a folder with server.js and public/ directory containing index.html and favicon.ico

2. Install dependencies

   Open terminal in project directory and run: npm init -y npm install express socket.io

3. Start the server

   node server.js

4. Access the application

   • Open browser and navigate to: http://localhost:33333
   • Or use your local IP address shown in console

🔧 Usage Guide

Joining the Chat

1. Enter a username in the input field
2. Press Enter or click outside the field
3. Read the chat rules displayed upon joining

Sending Messages

• Text: Type in the message box and press Enter/Send
• Images: Click the image button and select an image file
• Files: Click the file button and select any file type

Viewing Content

• Images: Click to view in full-screen modal
• Files: Click to see file details and download options

Online Users

• Right sidebar displays all connected users
• User count updates in real-time

⚙️ Technical Details

Server Configuration

• Port: 33333 (configurable in server.js)
• Host: 0.0.0.0 (accessible from network)
• CORS: Enabled for all origins
• File Limit: 10MB maximum per file

File Type Icons

The application displays appropriate icons for different file types:

• 📄 Documents (PDF, TXT, DOC)
• 📊 Spreadsheets (XLS, CSV)
• 🖼️ Images (JPG, PNG, GIF)
• 🎵 Audio (MP3, WAV)
• 🎬 Video (MP4, AVI)
• 📦 Archives (ZIP, RAR)
• ⚙️ Executables (EXE, MSI)

📡 Network Access

The server automatically detects and displays:

• Localhost URL: http://localhost:33333
• Local IP URL: http://[YOUR-IP]:33333
• Network access for other devices on the same network

🔒 Security Features

1. Input Validation: Basic client-side file size validation
2. Content Sanitization: HTML content handling
3. Connection Management: Proper user join/leave tracking
4. File Restrictions: 10MB size limit to prevent abuse

🐛 Troubleshooting

Common Issues

Port already in use: Change PORT variable in server.js line 144

Socket connection failed: Ensure firewall allows port 33333

Files not sending: Check file size (must be ≤10MB)

Users not appearing: Refresh browser or check console for errors

Development Mode

For debugging, add this to server.js after line 10: console.log('Debug: New connection from', socket.handshake.address);

📱 Browser Compatibility

• Chrome 60+ ✓
• Firefox 55+ ✓
• Safari 11+ ✓
• Edge 79+ ✓
• Mobile browsers ✓

🛠️ Development

Extending Features

To add new file type icons, modify the fileIcons object in server.js (lines 22-30):

const fileIcons = { // Add new mappings here 'py': '🐍', // Python files 'js': '📜', // JavaScript files 'html': '🌐', // HTML files // ... existing mappings };

Customizing Port

Change the PORT constant in server.js line 144: const PORT = 33333; // Change to desired port

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built with Express.js
• Real-time functionality powered by Socket.IO
• Icons from Unicode emoji set
• Gradient designs inspired by modern web trends

⚠️ Important Notes

1. This is a demonstration application - not suitable for production without additional security measures
2. All files are transferred as Base64 - consider chunking for large files
3. No persistent storage - messages are lost on server restart
4. No authentication - anyone can join with any username
5. Monitor server resources when sharing large files

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Enjoy chatting! For questions or issues, please check the console for error messages and ensure all dependencies are properly installed.