The Service Worker contains a mechanism by which it will postMessage
itself a signal to initialize its caches. Through this mechanism,
initialization happens asynchronously while keeping the SW process
alive.
Unfortunately in Firefox, the SW does not have the ability to
postMessage itself during the activation event. This prevents the
above mechanism from working, and the SW initializes on the next
fetch event, which is often too late.
Therefore, this change has the application wait for SW changes and
tells each new SW to initialize itself. This happens in addition to
the self-signal that the SW attempts to send (as self-signaling is
more reliable). That way even on browsers such as Firefox,
initialization happens eagerly.
Currently a bug exists where attempting to inject SwPush crashes the
application if Service Workers are unsupported. This happens because
SwPush doesn't properly detect that navigator.serviceWorker isn't
set.
This change ensures that all passive observation of SwPush and
SwUpdate doesn't cause crashes, and that calling methods to perform
actions on them results in rejected Promises. It's up to applications
to detect when those services are not available, and refrain from
attempting to use them.
To that end, this change also adds an `isSupported` getter to both
services, so users don't have to rely on feature detection directly
with browser APIs. Currently this simply detects whether the SW API
is present, but in the future it will be expanded to detect whether
a particular browser supports specific APIs (such as push
notifications, for example).
Currently, the way to not use the SW is to not install its module.
However, this means that you can't inject any of its services.
This change adds a ServiceWorkerModule.disabled() MWP, that still
registers all of the right providers but acts as if the browser does
not support Service Workers.
Observable.merge was called using .call() as if it were an operator
and not an Observable factory. This removes the .call() and uses
the factory properly.
PR Close#19962
Importing ServiceWorkerModule.register() will schedule registration of
the Service Worker inside an APP_INITIALIZER. Previously, the Promise
returned by navigator.serviceWorker.register() was returned from the
initializer function. This has the unwanted side effect of blocking
initialization until the SW is registered. Even worse, if the SW script
fails to load, this can cause the app initialization to fail.
The solution is to not return the registration promise from the
initializer function, essentially decoupling registration from the rest
of the initialization flow.
This change is not unit testable as there are no mocks/adapters yet for
navigator.serviceWorker. A future integration test should cover this case
with better fidelity.
PR Close#19936
Currently, the SwUpdate service doesn't receive messages from the SW.
This is because it attempts to subscribe to the 'message' event on
ServiceWorkerRegistration, when really messages are emitted by the
ServiceWorkerContainer.
This change moves to listening on ServiceWorkerContainer and changes
the mocks to reflect the way the browser actually works.
PR Close#19954
This service worker is a conceptual derivative of the existing @angular/service-worker maintained at github.com/angular/mobile-toolkit, but has been rewritten to support use across a much wider variety of applications.
Entrypoints include:
@angular/service-worker: a library for use within Angular client apps to communicate with the service worker.
@angular/service-worker/gen: a library for generating ngsw.json files from glob-based SW config files.
@angular/service-worker/ngsw-worker.js: the bundled service worker script itself.
@angular/service-worker/ngsw-cli.js: a CLI tool for generating ngsw.json files from glob-based SW config files.
Igor Minar
Fabian Wiles
Alex Rickabaugh
Trotyl