php-web-maker/packages/signup/signInWithPopup.js

setTimeout(() => {
	console.log('firing postmessag from iframe');
	//   window.top.postMessage('{"a":2}', "*");
}, 3000);

import { signInWithPopup, GoogleAuthProvider, getAuth } from 'firebase/auth';
import { initializeApp } from 'firebase/app';
import { config } from './firebaseConfig.js';

const app = initializeApp(config);
const auth = getAuth();

// This code runs inside of an iframe in the extension's offscreen document.
// This gives you a reference to the parent frame, i.e. the offscreen document.
// You will need this to assign the targetOrigin for postMessage.
const PARENT_FRAME = document.location.ancestorOrigins[0];

// This demo uses the Google auth provider, but any supported provider works.
// Make sure that you enable any provider you want to use in the Firebase Console.
// https://console.firebase.google.com/project/_/authentication/providers
const PROVIDER = new GoogleAuthProvider();

function sendResponse(result) {
	globalThis.parent.self.postMessage(JSON.stringify(result), PARENT_FRAME);
}

globalThis.addEventListener('message', function ({ data }) {
	if (data.initAuth) {
		// Opens the Google sign-in page in a popup, inside of an iframe in the
		// extension's offscreen document.
		// To centralize logic, all respones are forwarded to the parent frame,
		// which goes on to forward them to the extension's service worker.
		signInWithPopup(auth, PROVIDER).then(sendResponse).catch(sendResponse);
	}
});