Is it possible to use Firebase Cloud Messaging for two-way messaging from JS?
<p>In other words, I would like to use Firebase Cloud Messaging (FCM) from AngularJS to implement real-time chat.
If I understand it properly, this is not possible yet -- please correct me if I am wrong.</p>

<p>Currently two-way messaging (receive and send messages) via FCM can be done in <a href="https://firebase.google.com/docs/cloud-messaging/" rel="nofollow">Android SDK, iOS SDK, in Chrome Apps and Chrome plugins</a>. 
However JS frameworks (which fall under "Websites in Chrome") can benefit only from one-way push notifications, as stated <a href="https://firebase.google.com/docs/cloud-messaging/chrome/client" rel="nofollow">here</a>:</p>

<blockquote>
  <p>Websites in Chrome can implement push messaging through service workers and web app manifests following the Webpush standard.</p>
</blockquote>