React で WebSocket を使用したリアルタイム チャット アプリケーションを構築する

mkdir chat-backend  
cd chat-backend  
npm init -y  

npm install ws 

// server.js  
const WebSocket = require('ws');  

const wss = new WebSocket.Server({ port: 8080 });  

wss.on('connection', (ws) => {
    console.log('Client connected');  

    ws.on('message', (message) => {
        console.log(`Received: ${message}`);  
        // Broadcast the message to all clients
        wss.clients.forEach((client) => {
            if (client.readyState === WebSocket.OPEN) {
                client.send(message);  
            }
        });
    });  

    ws.on('close', () => {
        console.log('Client disconnected');  
    });
});  

console.log('WebSocket server running on ws://localhost:8080');  

node server.js

npx create-react-app chat-frontend  
cd chat-frontend  

// src/components/Chat.js  
import React, { useState, useEffect, useRef } from 'react';  

const Chat = () => {
    const [messages, setMessages] = useState([]);  
    const [input, setInput] = useState('');  
    const ws = useRef(null);  

    useEffect(() => {
        ws.current = new WebSocket('ws://localhost:8080');  

        ws.current.onmessage = (event) => {
            setMessages((prev) => [...prev, event.data]);  
        };  

        return () => {
            ws.current.close();  
        };
    }, []);  

    const sendMessage = () => {
        if (input.trim()) {
            ws.current.send(input);  
            setInput('');  
        }
    };  

    return (
        <div>



<ol>
<li>Use the Chat component in your App.js:
</li>
</ol>

<pre class="brush:php;toolbar:false">import React from 'react';  
import Chat from './components/Chat';  

function App() {
    return <Chat />;  
}  

export default App;  

npm start