I am new to electron and all the documentation on the electron docs use contextIsolation=false to enable port to be set globally on window object of the renderer.

I have 2 apps being served and loaded in electron using BrowserWindow with contextIsolation=true to limited access to app’s javascript.

Can MessageChannel be used to communicate between these 2 apps/BrowserWindows?

main.js

const { app, BrowserWindow, ipcMain } = require('electron');
const { MessageChannelMain } = require('electron/main');

let mainWindow;

app.on('ready', () => {
    mainWindow = new BrowserWindow({
        webPreferences: {
            contextIsolation: true,
            preload: path.join(__dirname, 'preload.js')
        }
    });

    mainWindow.loadURL('your-url');

    ipcMain.on('request-port', (event) => {
        const { port1, port2 } = new MessageChannelMain();
        event.sender.postMessage('port', null, [port2]);
        // You can now use port1 for communication in the main process
        port1.on('message', (event) => {
            console.log('Message from renderer:', event.data);
        });
    });
});

preload.js

const { contextBridge, ipcRenderer } = require('electron');

contextBridge.exposeInMainWorld('electronAPI', {
    requestPort: () => ipcRenderer.send('request-port')
});

window.addEventListener('message', (event) => {
    if (event.data === 'port') {
        const [port] = event.ports;
        window.messagePort = port;
        port.onmessage = (event) => {
            console.log('Message from main process:', event.data);
        };
    }
});

Here window.addEventListener(‘message’) is never executed. Also, the window object in the callback differs from the actual window object due to contextIsolation.

client.js

document.addEventListener('DOMContentLoaded', () => {
    window.electronAPI.requestPort();

    document.getElementById('sendMessage').addEventListener('click', () => {
        if (window.messagePort) {
            window.messagePort.postMessage('Hello from renderer!');
        }
    });
});