flex-layout: ObservableMedia: does not emit initial value in AOT mode

I’ve noticed a subtle difference in behavior in the ObservableMedia service when building with the CLI’s AOT mode being on vs off.

I have a component property that dictates the responsive display of a section of content, and it’s initialized via the subscription to the media change observable:

  constructor(private mediaQueryService: ObservableMedia) { }

  ngOnInit() {
      this.initializeFormOptions();
      this.initializeWatchers();
  }

  private initializeWatchers(): void {
    this.mediaWatcher = this.mediaQueryService
      .subscribe(mediaChange => {
        this.activeMediaViewport = mediaChange.mqAlias;
        this.lineEntryDisplayMode = this.calculateComponentDisplayMode(this.activeMediaViewport);
      });
  }

This works fine in non-AOT mode as the active mqAlias is available when the application loads. However, in AOT mode no value is emitted until a window resize event is triggered.

Since there is no direct query to the service available to get the current mqAlias, I am left with a less desirable brute force approach of querying individual possibilities using the isActive API method.