These docs are for an old release.
Info on upgrading to v5
displayEventEnd
Whether or not to display an event’s end time.
Boolean, default:
false // for dayGridMonth and dayGridWeek views
true // for timeGridWeek, timeGridDay, and dayGridDay
As noted above, each view has a specific default. Get fine-tuned control with View-Specific Options. A single boolean alone will set the value for all views.
If an event does not have an end date/time, or displayEventTime is false, it won’t be displayed anyway, regardless of this setting.