title: How to control if PWA uses cached version or fetches latest version?
body: <p>I have installed my PWA from Chrome and Firefox on Android, and from Safari on iOS. When I update my code on the website, I see quite different behaviour in the PWAs in terms of using older cached versions vs the newest one - Firefox-created PWA seems to require about 2-3 kill and restarts of the PWA, Chrome takes 5-6, and I couldn't get Safari-based PWA to start showing the newest version without deleting the PWA and re-adding to Home Screen from browser.</p>
  
  <p>Is there a spec that defines the conditions under which a newer, non-cached version is fetched? After much reading, I disabled the registering of my service worker, which should have made the PWAs network-only (no service-worker cache) but I continue to get old versions of the site served up in the PWAs. A normal browser window also seems to require multiple deep refreshes to get the new version, so I assume there is something besides the service worker that determines this?</p>