Method constructor

packages/service-worker/src/low_level.ts:141–213

(
    private serviceWorker: ServiceWorkerContainer | undefined,
    injector?: Injector,
  )

  readonly events: Observable<TypedEvent>;

  constructor(
    private serviceWorker: ServiceWorkerContainer | undefined,
    injector?: Injector,
  ) {
    if (!serviceWorker) {
      this.worker =
        this.events =
        this.registration =
          new Observable<never>((subscriber) =>
            subscriber.error(
              new RuntimeError(
                RuntimeErrorCode.SERVICE_WORKER_DISABLED_OR_NOT_SUPPORTED_BY_THIS_BROWSER,
                (typeof ngDevMode === 'undefined' || ngDevMode) && ERR_SW_NOT_SUPPORTED,
              ),
            ),
          );
    } else {
      let currentWorker: ServiceWorker | null = null;
      const workerSubject = new Subject<ServiceWorker>();
      this.worker = new Observable((subscriber) => {
        if (currentWorker !== null) {
          subscriber.next(currentWorker);
        }
        return workerSubject.subscribe((v) => subscriber.next(v));
      });
      const updateController = () => {
        const {controller} = serviceWorker;
        if (controller === null) {
          return;
        }
        currentWorker = controller;
        workerSubject.next(currentWorker);
      };
      serviceWorker.addEventListener('controllerchange', updateController);
      updateController();

      this.registration = this.worker.pipe(
        switchMap(() =>
          serviceWorker.getRegistration().then((registration) => {
            // The `getRegistration()` method may return undefined in
            // non-secure contexts or incognito mode, where service worker
            // registration might not be allowed.
            if (!registration) {
              throw new RuntimeError(
                RuntimeErrorCode.SERVICE_WORKER_DISABLED_OR_NOT_SUPPORTED_BY_THIS_BROWSER,
                (typeof ngDevMode === 'undefined' || ngDevMode) && ERR_SW_NOT_SUPPORTED,
              );
            }

            return registration;
          }),
        ),
      );

      const _events = new Subject<TypedEvent>();
      this.events = _events.asObservable();

      const messageListener = (event: MessageEvent) => {