Service workers

[Rich-Harris]

Closes #10.

One thing I realised: this gets a little tricky when paths.assets is specified, since service workers are scoped to their own parent 'directory'. The simplest solution, at least for now, is just to disable service workers if that option is specified.

Not quite sure how to test for this. I added a sample service worker to examples/sandbox though, and confirmed that it works offline. Would just need a compliant manifest.json to be a valid PWA.

[benmccann]

I might reverse this to reduce indentation:

if (url.protocol !== 'https:' && location.hostname !== 'localhost') {
  return;
}

[Rich-Harris]

Changed my mind about onFetch, and I think respondWith reads better as an if/else chain (since otherwise you have to do an early return as well as respondWith, but yeah, this would have been better

[benmccann]

One thing I realised: this gets a little tricky when paths.assets is specified, since service workers are scoped to their own parent 'directory'

We've had issues in Sapper with the base option specified as well

[benmccann]

Can remove

kit/packages/kit/src/core/create_app/index.js

Line 53 in 5416bd7

export function create_serviceworker_manifest({

?

Might need to slightly update the docs:
https://github.com/sveltejs/kit/blob/3c4c1980e7db0d890049d6fb155b03f1fabf0764/documentation/docs/01-structure.md
https://github.com/sveltejs/kit/blob/84d9a7dcd2a4d8341dfe03275c98a4e9c27bf546/documentation/docs/11-deploying.md

[Rich-Harris]

We've had issues in Sapper with the base option specified as well

Can you elaborate?

[Rich-Harris]

Good catch, removed create_serviceworker_manifest.

I had a change of heart about onFetch etc. Deep down I think I knew I would. event.respondWith is regrettable, but the cost of adding the helper functions isn't worth it.

[benmccann]

Here are the Sapper issues: sveltejs/sapper#1538 and sveltejs/sapper#1441. Not sure there's too much to be aware of here except that if we want to support base it's a case worth testing

[Rich-Harris]

Ah ok. That should work just fine, since base is prepended to the build and assets arrays. The one place it gets a little tricky is if you test it with npm start, because in that case base and assets are disregarded. But that's a larger issue than just service workers