1. Observe("selectedDate")
void selectedDateChanged([_])

Source

@Observe("selectedDate")
void selectedDateChanged([_]) {
  _logger.fine("Date changed : ${selectedDate}");
  String newText;
  if (selectedDate!=null) {
    newText = format.format(selectedDate);
  } else {
    newText = null;
  }

  if (newText==textDate||_comingFromTextChange) {
    _comingFromTextChange = false;
    return;
  }
  textDate = newText;
  _logger.fine("Selected Date is ${selectedDate}");
  dispatchEvent(new CustomEvent("selectdate"));
  dispatchEvent(new CustomEvent("select-date-changed"));

}