The partStart() method returns the start of the currently visible event part as a DayPilot.Date value.
DayPilot.Event.partStart()This method has no parameters.
There are two cases when the visible event box does not represent the full event duration:
The overnight events will be shown as two or more event parts, each in one day.
If non-business hours are hidden and the event starts or ends in the non-business hours.
In these cases, partStart() can return a different value than start().
const visibleStart = e.partStart();