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Project 02: Real-time Chat Application

Phase 1: Solidifying Fundamentals
Why This Project?

Real-time features are everywhere - chat apps, live notifications, collaborative tools, live sports scores. Understanding how real-time communication works is essential for modern web developers.

This project teaches you WebSockets, which is different from regular HTTP requests. With HTTP, the client asks and the server answers. With WebSockets, both can send messages anytime, which is perfect for chat and live updates.

You'll learn how to manage connections, handle users joining and leaving, and keep everything synchronized across multiple users. These are skills you'll use in many real-world applications.

Overview

Create a multi-room chat system with WebSocket connections for real-time communication. This project introduces you to bidirectional communication between client and server, teaching you how to handle stateful connections and synchronize state across multiple clients.

You'll build both a server that manages WebSocket connections and a client interface that allows users to join rooms, send messages, and see who's online in real-time.

Learning Objectives

Understand WebSocket protocol and how it differs from HTTP

Manage stateful connections and handle disconnections gracefully

Synchronize state across multiple connected clients

Handle real-time events and emit messages to specific users or rooms

Persist chat history in a database

Build a responsive chat interface with React

Core Requirements

WebSocket server using Socket.io

Multiple chat rooms that users can join and leave

Real-time message delivery to all users in a room

Display list of online users in current room

Store message history in MongoDB

Load previous messages when joining a room (last 50 messages)

Show typing indicators when someone is typing

Display timestamps for each message

Handle user disconnections and reconnections

Frontend Requirements

Room selection screen showing available rooms

Chat interface with message list, input field, and online users sidebar

Auto-scroll to newest messages unless user has scrolled up

Visual distinction between own messages and others' messages

Show system messages (user joined, user left)

Responsive design that works on mobile and desktop

Socket Events to Implement

connection - Handle new user connection

join_room - User joins a specific room

leave_room - User leaves current room

send_message - User sends a message to room

typing_start - User starts typing

typing_stop - User stops typing

disconnect - Handle user disconnection

get_room_users - Retrieve list of users in room

Technical Challenges

Manage socket connections in server memory (Map or object)

Handle race conditions when multiple users join/leave simultaneously

Implement debouncing for typing indicators

Ensure messages are delivered in correct order

Clean up resources when users disconnect

Handle reconnection logic on client side

Prevent duplicate message delivery

Data Models

Message: id, roomId, username, text, timestamp

Room: id, name, createdAt (can be hardcoded or dynamic)

User session: socketId, username, currentRoom, joinedAt

Bonus Features

Allow users to create new rooms dynamically

Add message reactions (thumbs up, heart, etc.)

Implement direct messaging between users

Add file/image sharing capability

Show "read receipts" or "delivered" status

Add username mentions with @ symbol

Implement message editing and deletion

Helpful Resources

Socket.io Basics: Official Socket.io documentation at socket.io. Start with the "Get Started" guide.

WebSocket vs HTTP: Search for "WebSocket explanation" or "real-time web explained". Understanding the difference is important.

React with Socket.io: Look for tutorials on "React Socket.io integration" or "useEffect with Socket.io".

Event Handling: Socket.io uses events. Read about emit() and on() methods in the docs.

Room Management: Socket.io rooms documentation shows how to group users together.

Helpful Resources

Socket.io Basics: Official Socket.io documentation at socket.io. Start with the "Get Started" guide.

WebSocket vs HTTP: Search for "WebSocket explanation" or "real-time web explained". Understanding the difference is important.

React with Socket.io: Look for tutorials on "React Socket.io integration" or "useEffect with Socket.io".

Event Handling: Socket.io uses events. Read about emit() and on() methods in the docs.

Room Management: Socket.io rooms documentation shows how to group users together.

Success Criteria

Multiple users can chat in the same room simultaneously

Messages appear instantly for all users in the room

Online users list updates in real-time

Previous messages load when joining a room

Application handles disconnections without crashing

Typing indicators work smoothly without lag

No messages are lost during normal operation

Learning Resources

Study Socket.io documentation and event handling patterns

Research WebSocket vs HTTP long-polling

Look into React hooks for managing WebSocket connections

Explore patterns for handling real-time state updates

Learn about debouncing and throttling for performance

Hint: Start with the simplest version first - a single room where users can send messages. Get that working perfectly before adding features like multiple rooms, typing indicators, and message persistence.

Use useEffect to establish the Socket.io connection when the component mounts, and clean it up when it unmounts. Remember to handle the case where a user closes the browser tab suddenly.

Submit Your Project

Once you've completed this project, submit your GitHub repository link below: