Building a Chat Interface with Polling or WebSockets

Table of Contents

1. Introduction
2. Real-Time Communication: Polling vs WebSockets
3. Setting Up the React Project
4. Creating the Chat UI
5. Polling-Based Implementation
6. WebSocket-Based Implementation
7. Optimizing Chat State Management
8. Handling Edge Cases
9. Security Considerations
10. Scalability and Production Concerns
11. Conclusion

1. Introduction

Real-time applications like chat interfaces are among the most common use cases in modern web development. With React, building a responsive and performant chat app is achievable, but the real-time communication layer needs careful planning. You can choose between polling and WebSockets depending on your requirements and infrastructure.

This module will guide you through building a chat interface from scratch using both techniques, comparing their pros and cons, and ensuring best practices are followed.

2. Real-Time Communication: Polling vs WebSockets

Polling

• Periodically sends requests to the server to fetch new messages.
• Easier to implement, but can be inefficient.
• May lead to delayed message delivery.

WebSockets

• Maintains a persistent, bidirectional connection.
• Ideal for instant messaging, gaming, collaborative apps.
• Requires a backend that supports WebSockets (e.g., Node.js with ws, or Socket.io).

3. Setting Up the React Project

Use Vite or Create React App:

bashCopyEditnpm create vite@latest react-chat --template react
cd react-chat
npm install

Install dependencies:

bashCopyEditnpm install axios socket.io-client

4. Creating the Chat UI

Basic component structure:

jsxCopyEditconst Chat = ({ messages, onSendMessage }) => {
  const [input, setInput] = useState("");

  const handleSubmit = (e) => {
    e.preventDefault();
    onSendMessage(input);
    setInput("");
  };

  return (
    <div className="chat-container">
      <div className="messages">
        {messages.map((msg, idx) => (
          <div key={idx} className="message">{msg}</div>
        ))}
      </div>
      <form onSubmit={handleSubmit}>
        <input 
          value={input}
          onChange={(e) => setInput(e.target.value)} 
          placeholder="Type a message..." 
        />
        <button type="submit">Send</button>
      </form>
    </div>
  );
};

5. Polling-Based Implementation

Polling uses a setInterval to fetch new messages at a regular interval.

jsxCopyEdituseEffect(() => {
  const fetchMessages = async () => {
    const res = await axios.get('/api/messages');
    setMessages(res.data);
  };

  fetchMessages(); // Initial fetch
  const interval = setInterval(fetchMessages, 3000); // Every 3 seconds

  return () => clearInterval(interval);
}, []);

Sending messages:

jsCopyEditconst onSendMessage = async (msg) => {
  await axios.post('/api/send', { message: msg });
};

Polling is stateless and easy to set up but adds unnecessary load on the server and doesn’t provide true real-time UX.

6. WebSocket-Based Implementation

Install WebSocket client:

bashCopyEditnpm install socket.io-client

Connect to the socket server:

jsCopyEditimport { useEffect, useState } from 'react';
import { io } from 'socket.io-client';

const socket = io('http://localhost:3001');

const ChatSocket = () => {
  const [messages, setMessages] = useState([]);

  useEffect(() => {
    socket.on('message', (msg) => {
      setMessages((prev) => [...prev, msg]);
    });

    return () => socket.disconnect();
  }, []);

  const onSendMessage = (msg) => {
    socket.emit('send', msg);
  };

  return <Chat messages={messages} onSendMessage={onSendMessage} />;
};

You’ll need a server like this:

jsCopyEdit// Node.js + Socket.io backend
const io = require('socket.io')(3001, {
  cors: { origin: '*' }
});

io.on('connection', (socket) => {
  socket.on('send', (msg) => {
    io.emit('message', msg);
  });
});

WebSockets allow true real-time communication, fewer requests, and a better UX.

7. Optimizing Chat State Management

• Use useRef to keep track of the last message or scroll position.
• Store messages in a normalized structure if chat gets complex.
• Use immer, zustand, or Redux for managing large state trees if necessary.

8. Handling Edge Cases

• Handle connection loss with WebSockets (socket.on("disconnect"))
• Retry sending messages when offline
• Support optimistic UI updates (display the message before it reaches the server)
• Validate user input to avoid injection attacks

9. Security Considerations

• Use JWT authentication with WebSockets and API endpoints.
• Always sanitize incoming and outgoing messages.
• Implement rate limiting on the server side.
• Validate socket connection origins.

10. Scalability and Production Concerns

• WebSockets require sticky sessions or Redis pub-sub in clustered deployments.
• Use Redis, Kafka, or NATS for scaling real-time data handling.
• Integrate chat logs with a database like MongoDB, PostgreSQL, or Firebase.
• Consider fallback mechanisms: fallback to polling if WebSocket fails.

11. Conclusion

React makes it straightforward to build chat UIs, but the communication method greatly affects the UX and performance. While polling is easier for MVPs, WebSockets are the gold standard for scalable, real-time chat.

You can now decide based on your app’s scope, whether to start with polling or go directly with WebSockets. Either way, this module provides the foundation you need to build a robust chat feature in your React app.