..
dayClick: function(date, allDay, jsEvent, view) {
            $('#calendar').fullCalendar('clientEvents', function(event) {
                // match the event date with clicked date if true render clicked date events
                if(event.rendering == 'background'){
                    if (moment(date).format('YYYY-MM-DD') == event.start.format('YYYY-MM-DD')) {
            // do your stuff here
            $("#instructions").html(moment(date).format('YYYY-MM-DD')+': on ' +event.title+' shift.')
                    }
                }
            });
}
..