:building_construction: Don't register service worker in localhost

[resir014]

This prevents the inevitable fact that any other local apps that use the same port as ours will be overriden by Bemuse's service worker.

[codecov-io]

Codecov Report

Merging #504 into master will not change coverage. The diff coverage is n/a.

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  Hits         4531    4531           
  Misses        856     856

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[resir014]

We do need to find a way to test our service workers, still. Maybe moving it to our staging URL also works. What do you think?

[dtinth]

@resir014 Yes, I would prefer that we can test our service workers locally.

Solutions that came up to my mind is:

1. Make service worker self-destruct itself if it has determined that the server is no longer running Bemuse. Here’s how to self-destruct a service worker: https://github.com/NekR/self-destroying-sw

2. On localhost make service worker registration opt-in.

3. Move Bemuse server to a different port so that it less likely clash with other apps.

These solutions can be combined.

I would prefer doing option 1 as it would keep service worker on by default, but makes sure it only stays for Bemuse development.

[resir014]

@dtinth Hmm, I'm not sure I'm understanding the code examples for the first approach. Sure it self-destructs, but I don't see where we can put our service worker + its caching strategies.

Also, I had a (now-deleted) local branch to rewrite most of our service worker code with Workbox. I initially deleted it because I didn't go far with it, but now that we're working on this PR, I could look into it again.

[dtinth]

@resir014 Here’s an example strategy:

When a service worker is activated, make a fetch request to, e.g. /bemuse.txt or some special file that identifies the Bemuse project. If server returns 404, it means that the current server is no longer running Bemuse. In this case service worker self-destructs.

(Note that I look specifically for 404, since we want Bemuse to continue working offline if no server is running, so we make SW self-destruct only if the server runs a different project.)

[resir014]

@dtinth Alright, I'll close this PR and redo it with the method mentioned above.