onChange Catalog Client Script oldValue is empty

[PabloL]

Hi Community! Happy New Year!

I wrote an onChange catalog client script on a Variable named "Pickup Choice". This variable is type "Select Box" and has a choice list with choices like "Pickup" and "Ship to my Location".

The purpose of this script is to clear the mandatory status of the comments variable, which is made mandatory by a UI Action before the pickup choice is changed.

My issue that I found is that I tried to make the client script run only when oldValue == "Ship to my location" to signify the user selecting a different choice. However, I noticed that when I selected a new option, the oldValue was empty (but the newValue was correctly populated with the new choice).

Why could I not have access to oldValue? I'm trying to do this from the Platform UI with UI16 on a simple Catalog Item.

[Domi727]

As a workaround, I cache the last known value in sessionStorage and treat that as the “previous value” on subsequent onChange events:

function onChange(control, oldValue, newValue, isLoading) {
   if (isLoading || newValue == '') {
      sessionStorage.clear()
      return;
   }
	var oldItemValue = sessionStorage.getItem('item');
	sessionStorage.setItem('item', newValue);

	if (oldItemValue) {
		// code here...
	} else {
		// code here...
	}
}