React でブロードキャスト チャネル API を使用する方法

import { useEffect, useState } from 'react';

const useBroadcastChannel = (channelName) => {
    const [message, setMessage] = useState(null);
    const channel = new BroadcastChannel(channelName);

    useEffect(() => {
        const handleMessage = (event) => {
            setMessage(event.data);
        };

        channel.onmessage = handleMessage;

        // Clean up the channel when the component unmounts
        return () => {
            channel.close();
        };
    }, [channel]);

    const sendMessage = (msg) => {
        channel.postMessage(msg);
    };

    return { message, sendMessage };
};

export default useBroadcastChannel;

import React, { useEffect } from 'react';
import useBroadcastChannel from './useBroadcastChannel';

const AuthManager = () => {
    const { message, sendMessage } = useBroadcastChannel('auth_channel');

    const handleLogin = () => {
        // Notify all tabs that the user has logged in
        sendMessage({ type: 'login', user: 'JohnDoe' });
    };

    const handleLogout = () => {
        // Notify all tabs that the user has logged out
        sendMessage({ type: 'logout' });
    };

    useEffect(() => {
        if (message) {
            if (message.type === 'logout') {
                alert('You have been logged out in another tab!');
            }
        }
    }, [message]);

    return (
        <div>
            <h1>Authentication Manager</h1>
            <button onClick={handleLogin}>Log In</button>
            <button onClick={handleLogout}>Log Out</button>
        </div>
    );
};

export default AuthManager;