CalendarFull stop overlapping events

gistfile1.js

function isOverlapping (event){
    // "calendar" on line below should ref the element on which fc has been called
    var array = calendar.fullCalendar('clientEvents');
    for(var i in array){
  		if(event._id !== undefined && array[i]._id == event._id) {
  			continue
  		} else {
  			var arrayEnd = ((array[i].end === null) ? array[i].start.clone().add('days', 1) : array[i].end)
  				, eventEnd = ((event.end === null) ? event.start.clone().add('days', 1) : event.end)

  			if ((array[i].allDay === true && event.start >= array[i].start && event.start < arrayEnd) // If the event is on the same day as an all day event
  				|| (event.allDay === true && array[i].start >= event.start && array[i].start < eventEnd) // If the all day event is on the same day as an event
  				|| (event.allDay === undefined && array[i].start >= event.start && array[i].start < event.end) // if the event is an all day event on the same day as an all day event
  				|| (event.end > array[i].start && event.start < array[i].end) // If event on the same day
  				){
        	return true;
      	}
  		}
    }
    return false;
}