title: ajaxStart and ajaxStop equivalent with fetch API
body: <p>I'm trying to migrate my API calls from using jQuery ajax to using the Fetch API.</p>
  
  <p>I was using jQuery ajaxStart and ajaxStop to display a loading spinner during server calls.</p>
  
  <p>I'm running several parallel server requests, I want the spinner to start when the first request start and to stop when the last request settled.</p>
  
  <p>It was pretty straight foward with jQuery. However, I can't find a similiar technique using the fetch API.
  Any ideas ?</p>