startDate and endDate should be type Date

[kutyel]

Currently I have to do this to work with this component:

  const onDateChange = ({ startDate }: { startDate: number }) =>
    (selectedDate = new Date(startDate))

whereas a more proper solution would be to bind to something like this which cally is doing:

onfocusday={(e: CustomEvent<Date>) => (selectedDate = e.detail)}

Is this too tricky or just a preference?