Method getLazyEmitter

src/google-maps/map-event-manager.ts:52–97

* Gets an observable that adds an event listener to the map when a consumer subscribes to it. * @param name Name of the event for which the observable is being set up. * @param type Type of the event (e.g. one going to a DOM node or a custom Maps one).

(name: string, type?: 'custom' | 'native')

   * @param type Type of the event (e.g. one going to a DOM node or a custom Maps one).
   */
  getLazyEmitter<T>(name: string, type?: 'custom' | 'native'): Observable<T> {
    return this._targetStream.pipe(
      switchMap(target => {
        const observable = new Observable<T>(observer => {
          // If the target hasn't been initialized yet, cache the observer so it can be added later.
          if (!target) {
            this._pending.push({observable, observer});
            return undefined;
          }

          let handle: ListenerHandle;
          const listener = (event: T) => {
            this._ngZone.run(() => observer.next(event));
          };

          if (type === 'native') {
            if (
              (typeof ngDevMode === 'undefined' || ngDevMode) &&
              (!target.addEventListener || !target.removeEventListener)
            ) {
              throw new Error(
                'Maps event target that uses native events must have `addEventListener` and `removeEventListener` methods.',
              );
            }

            target.addEventListener!(name, listener);
            handle = {remove: () => target.removeEventListener!(name, listener)};
          } else {
            handle = target.addListener(name, listener)!;
          }

          // If there's an error when initializing the Maps API (e.g. a wrong API key), it will
          // return a dummy object that returns `undefined` from `addListener` (see #26514).
          if (!handle) {
            observer.complete();
            return undefined;
          }

          this._listeners.push(handle);
          return () => handle.remove();
        });

        return observable;
      }),
    );
  }

  /** Sets the current target that the manager should bind events to. */
  setTarget(target: MapEventManagerTarget) {