//Create observable from the window event
this._resize$ = Observable.fromEvent(window, 'resize')
  .pipe(
    debounceTime(200),
    map(() => window.innerWidth), //Don't use mapTo!
    distinctUntilChanged(),
    startWith(window.innerWidth),
    tap(width => this.sb.setWindowWidth(width)),
  );
this._resize$.subscribe();