Get oldEvent info from FullCalendar

I have eventResize and eventDrop functions like this. How to get the existing event’s old start and datetime that is being dragged to new date or is being resized?

var calendar = new Calendar(calendarEl, {

events: [
 // events here
],

editable: true,

eventDrop: function(info) {
    alert(info.event.title + " was dropped on " + info.event.start.toISOString());

    if (!confirm("Are you sure about this change?")) {
      info.revert();
    }
},
eventResize: function(info) {
  alert(info.event.title + " end is now " + info.event.end.toISOString());

  if (!confirm("is this okay?")) {
   info.revert();
  }
 }

 });