Sets whether an event is considered all-day.
event.setAllDay( bool, [ settings ] )
bool must be
If converting to
allDay:false, if the event’s start and end dates will have their times set to 00:00:00.
If there are other events that share the same
groupId, those events’ dates will be similarly modified.
settings object is an optional parameter that can contain a single flag:
maintainDuration- operates the same way as allDayMaintainDuration