Make Ruby on Rails work offline
InstantPWA hosts a fallback service worker and manifest for Ruby on Rails, so pages you've already visited keep working offline without you writing cache logic yourself. Add the snippet to app/views/layouts/application.html.erb via application.html.erb <head> and the worker registers automatically on first visit.
Steps
- 1
Open app/views/layouts/application.html.erb
Go to application.html.erb <head>.
- 2
Paste the InstantPWA snippet
Drop the one-line async script tag in the Ruby on Rails head section — no build step or dependency install.
- 3
Let the service worker register
No manifest.json or sw.js to write — InstantPWA serves both and scopes the worker to your site's root.
- 4
Test offline mode
Visit a page once, then use DevTools → Network → Offline (or airplane mode on a phone) and reload to confirm cached pages still render.
- 5
Verify on a phone
Open your live Ruby on Rails URL on a mobile device (not the editor preview) to confirm the popup renders.
Constraints to know
- Turbo Drive keeps the <head> element persistent across page-to-page navigation, so the snippet initializes once per session rather than re-running on every Turbo visit — this is a feature, not a bug, but means you should test with a full page load first.
- The script tag doesn't need to be pinned in config/importmap.rb since it's a plain external <script>, not an ES module import.
FAQ
Do I need to write my own service worker?+
No — InstantPWA hosts a fallback manifest and service worker automatically if your site doesn't already ship one.
What happens to pages I haven't visited yet?+
They won't be available offline until visited at least once — InstantPWA caches on-visit rather than pre-caching your entire site.
Does offline mode change how Ruby on Rails serves pages normally?+
No — the service worker only intercepts requests when the browser is offline; online visits behave exactly as before.