observable-host-listener-1.ts

@Directive({
  selector: '[mouseClick]'
})
export class MouseClickDirective implements OnInit {
  private readonly clicks$ = new Subject<MouseEvent>();
  private readonly someStream$: Observable<any>;

  @HostListener('click', ['$event']) handleClick(click: MouseEvent) {
    this.clicks$.next(click);
  }

  ngOnInit() {
    this.someStream$ = this.clicks$.pipe(
      // do meaningful stuff here
    );
  }
}