When does the openWindow promise resolve? #728
Description
I am trying to send a message to a page from a serviceWorker. The goal is to let the page respond to the click (opening what the notification is about).
With this code inside a notificationclick event handler:
clients.openWindow(url).then(function(client) {
client.postMessage(message);
});There is a race between delivering the message event and attaching the message event listener (while loading the page). Experimentally, I have found that the only way to receive the event is to add the message event listener before <html>, like so:
<!DOCTYPE html>
<script>
navigator.serviceWorker.addEventListener('message', function (event) {
console.log('got message:', event.data);
});
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
(...)This appears very unreliable to me (tested in Chrome for Android version 44 and 45).
A possible solution is letting the promise resolve around the DOMContentLoaded or load events. Another option could be to let the service worker detect when the page is loaded (via an event).
I have used a workaround: sending the needed information in the URL fragment identifier and navigating to the proper URL using history.replaceState in the client (webpage). This works reliable so far.