The Core Progressive Web App checklist says that a PWA
should provide a custom offline page. The Optimial Progressive Web App checklist
says that a PWA should provide an offline experience where the PWA works the same offline as
it does online (wherever network connectivity isn't strictly required).
Learn more in the What is network reliability and how do you measure it? post.
How the Lighthouse offline audit fails
flags pages that don't respond with an
HTTP 200 response
Lighthouse emulates an offline connection using the Chrome Remote Debugging Protocol
and then attempts to retrieve the page using
How to make your PWA work offline
- Add a service worker to your app.
- Use the service worker to cache files locally.
- When offline, use the service worker as a network proxy to return the
locally cached version of the file.