Rxjs Universal drag event

DragEvent.ts

export const DragEvent = (selector:string):Observable<boolean> => {
 
  //element where the drag event should be recorded (make sure element is in the dom)
  const elem = document.querySelector(selector);

  // touch events to handle mobile devices
  const touchStart$ = fromEvent<TouchEvent>(elem, 'touchstart');

  const touchEnd$ = fromEvent<TouchEvent>(elem, 'touchend');

  const touchMove$ = fromEvent<TouchEvent>(elem, 'touchmove');

  // mouse events for desktop users
  const mouseDown$ = fromEvent<MouseEvent>(elem, 'mousedown');

  const mouseUp$ = fromEvent<MouseEvent>(elem, 'mouseup');

  const mouseMove$ = fromEvent<MouseEvent>(elem, 'mousemove');

  //Mouse drag event
  const mouseDragging$ = mouseMove$.pipe(
    skipUntil(mouseDown$),
    takeUntil(mouseUp$)
  );

  // 
  const mapToBoolean = (bool) => map(() => bool);

  //universal drag event will emit true on drag (desktop/mobile) optional:add touchStart$ to the merge.
  const move$ = merge(mouseDragging$, touchMove$).pipe(mapToBoolean(true);

  //universal end of drag event will emit false on drag end (desktop/mobile)
  const end$ = merge(mouseUp$, touchEnd$).pipe(mapToBoolean(false);

  //merged to return true or false depending on user dragg
  return merge(move$, end$).pipe(distinctUntilChanged());

}