observable

var observableClickDown$ = fromEvent(document, 'mousedown', { passive: false });
var observableMove$ = fromEvent(document, 'mousemove', { passive: false });
var observableClickUp$ = fromEvent(document, 'mouseup', { passive: false });

var chained$ = observableClickDown$.pipe(
  switchMap((val: MouseEvent) => 
    observableMove$.pipe(
      takeUntil(observableClickUp$),
      timeout(2500),
      catchError(error => of('Timed out'))
      )
  ),
  catchError(error => of(error))
);

chained$.subscribe(val => console.log(val), err => console.log("ERROR: " + err));