nextDayThreshold

When an event’s end time spans into another day, the minimum time it must be in order for it to render as if it were on that day.

Only affects timed events that appear on whole-days. Whole-day cells occur in DayGrid views and the all-day slots in the TimeGrid views.

For example, if nextDayThreshold were '09:00' (9am), the following event would appear to take up only one day:

  var calendar = new Calendar(calendarEl, {
    // other options...
    nextDayThreshold: '09:00:00',
    events: [
      {
        // Goes from 8pm to 2am the next day.
        title: 'Event 1',
        start: '2014-02-04T20:00:00',
        end: '2014-02-05T02:00:00'
      }
    ]
  });

Whereas, the following event would appear to take up two days:

  var calendar = new Calendar(calendarEl, {
    // other options...
    nextDayThreshold: '09:00:00',
    events: [
      {
        // Goes from 8pm to 10am the next day.
        title: 'Event 2',
        start: '2014-02-04T20:00:00',
        end: '2014-02-05T10:00:00'
      }
    ]
  });

It is important to stress that this nextDayThreshold option, set on the Calendar itself, is ignored when allDay is true. Generally, as discussed when defining an Event object, allDay, start and end properties are sufficient for specifying an event that lasts an entire day.

However, when allDay is false, this additional nextDayThreshold property allows an override of the default behaviour of exclusive end dates by setting the cut-off point (or minimum) for the event to be rendered on that date.