Use a Sevice Worker to improve low-bandwidth/offline experience

[jankeromnes]

Implementing a service worker in the Janitor web app could significantly improve subsequent load times, and make it (somewhat) usable offline.

[jankeromnes]

A basic service worker was added in 6468bda, but it doesn't provide caching yet.

[Coder206]

@jankeromnes Would this be similar to what you are looking for: https://serviceworke.rs/strategy-cache-update-and-refresh.html or perhaps https://github.com/GoogleChrome/sw-precache ?

[jankeromnes]

Yes, we're looking to achieve similar results, but we don't have a build system to hook into (and we probably won't have, as HTTP 2 will remove the need for bundle resources).

Additionally, we might need custom caching logic, because resources like /img/*.svg should always be cached, but API calls like /$spawn or the upcoming /api/hosts should often not be cached, and we should handle offline requests to these differently. I'm not sure yet what the best way to deal with API calls with a Service Worker is.

[nt1m]

@jankeromnes I don't think this is essential for the beta release tbh.

[jankeromnes]

@nt1m I'm worried that the more we work on the website without writing a service worker, the harder it will become to eventually write one. But you're right, it's not a hard requirement and it shouldn't block the beta release. Let's remove the issue from the milestone.

[jankeromnes]

@Coder206 found this, which could help: https://www.pwabuilder.com/