feat(service-worker): Support ignoring specific URLs

🚀 feature request

Relevant Package

This feature request is for @angular/service-worker

Description

While forcing the SW to ignore specific URL is now possible adding http header ngsw-bypass or ngsw-bypass=true as query param, it’s not possible to specify some URLs to be ignored. This would be very useful when dealing with SDKs like Firestore, that don’t allow to edit the http requests.

Describe the solution you’d like

As discussed in #21191 some workarounds are possible : #21191 (Comment) or 21192 (Comment).

Second comment also contains a suggestion on how to modify SW in order to implement the requested feature. This would mean accepting messages to allow to set a list of URLs to ignore.

[gkalpak]

WRT https://github.com/angular/angular/issues/30195#issuecomment-492373860: Although there are no immediate plans, we are considering/investigating ways to make the SW more flexible and extensible. It will take a significant refactoring, though, so not going to happen overnight 😁

WRT https://github.com/angular/angular/issues/30195#issuecomment-492383256: Anything involving ngsw-config.json is async (i.e. the SW needs to retrieve the config from the Cache) and thus can’t be used to make a sync decision in onFetch.

[petersalomonsen]

Another idea:

Add property in ngsw-config.jsonpointing to a .js file containing app-specific code to be executed in the serviceworker (onFetch event). That would be a simple but powerful addition that keeps the SW script independent of the app version, and does not involve code evaluation on the fly.