<script>
    document.addEventListener('DOMContentLoaded', function() {
        var calendarEl = document.getElementById('calendar');
        var calendar = new FullCalendar.Calendar(calendarEl, {
            plugins: [ 'dayGrid','timeGrid', 'interaction', 'list' ],
            height: 800,
            header: {
                left: 'prev,today,next',
                center: 'title',
                right: 'dayGridMonth,timeGridWeek,listMonth'
            },
            buttonText: {
                today: 'Hoy',
                month: 'Mes',
                agendaWeek: 'Semana',
                agendaDay: 'Dia'
            },
            axisFormat: 'HH:mm',
            timeFormat: 'HH:mm',
            editable: false,
            droppable: false,
            eventTextColor:"#FFF",
            eventColor:"#337AB7",
            selectable: true,
            selectHelper: true,
            eventLimit: 4,
            eventDurationEditable: false,
            locale: 'es',
            timeZone: 'UTC -4',
            themeSystem: 'themeSystem',
            defaultView: 'dayGridMonth',
            nowIndicator: true,
            events:
                function ( start, end, timeZoneStr, callback ){
                    $.ajax({
                      type:'get',
                      url:'{{ route("load_calendar")}}',
                      success: function (data){
                        callback(data);
                      }
                    })
                  }
        })
        calendar.render();
});
</script>

public function load_calendar(){

        $all_event = calendarModel::all()->toArray();


        $event_data=array();

        foreach ($all_event as $key => $event_val) {

            $event_data[$key]['title'] =$event_val['event_titulo'];
            $event_data[$key]['start'] =date('d/m/Y H:i:s', strtotime($event_val['event_fecha_inicio']));
            $event_data[$key]['end']  =date('d/m/Y H:i:s', strtotime($event_val['event_fecha_final']));

            $event_data[$key]['start_formate'] =date('d/m/Y H:i:s', strtotime($event_val['event_fecha_inicio']));
            $event_data[$key]['end_formate']  =date('d/m/Y H:i:s', strtotime($event_val['event_fecha_final']));


            $event_data[$key]['events_id'] = $event_val['id'];
            $event_data[$key]['event_description'] =$event_val['event_descripcion'];
            $event_data[$key]['created_at'] =date('d/m/Y', strtotime($event_val['created_at']));
            $event_data[$key]['updated_at'] =date('d/m/Y', strtotime($event_val['updated_at']));

        }

            return $event_data;

    }

echo json_encode($event_data);
dump($event_data);

return response()->json($event_data);

events: '{{ url("load_calendar" )}}'

return response()->json($event_data);

return $event_data;