目前在幫網站加上PWA功能，但研究好幾天還是搞不定，特來求救...
SW啟動狀態，但好像要到網站才會顯示通知，是否還要加上Firebase?
而A2HS沒反應?

<script>
if( 'serviceWorker' in navigator )
{
	window.addEventListener('load', function() {
		navigator.serviceWorker.register('sw.js');
		if( Notification.permission !== 'granted' )
			Notification.requestPermission();
	});
}

var deferredPrompt;
window.addEventListener('beforeinstallprompt', function(e)
{
	e.preventDefault();
	deferredPrompt = e;
	document.querySelectorAll("div").addEventListener('click', function()
	{
		deferredPrompt.prompt();
		deferredPrompt = null;
	});
});
</script>

sw.js

if( Notification.permission === 'granted' )
	fetch('sw').then(function(response) {
		response.text().then(function(text) {
			if( text ) self.registration.showNotification("系統通知", { body: "您有 "+text+" 筆未讀訊息", icon: "logo.png" });
		});
	});

self.addEventListener('notificationclick', function(event)
{
	event.notification.close();
	event.waitUntil(clients.openWindow('https://...'));
});