ValueChanging プロパティ (DropDownClientEvents)

// The client event 'ValueChanging' takes two parameters sender and e
// sender  is the object which is raising the event
// e is the DropDownEditEventArgs
  function WebDropDown_ValueChanging(sender, e) {
      //Gets the new value in the  value display
      var newValue = e.getNewValue();

      //Gets the old value in the value display
      var oldValue = e.getOldValue();

      if (!confirm("Are you sure you want to change the curent value from '"+ oldValue+"' to"+newValue+"?"))
      //Cancels the ValueChanging client event 
          e.set_cancel(true);
  }