Unselect all items of a list field

I tryed to unselect via javaScript all items of a list field setting "currentValueIndices" to -1 but it seems that doesn't work.

The setting works fine to indicate the selected item(s) with a number or an array, but doesn't work for unselect all of them, whereas -1 is the value returned if no items are selected...

Is there an other way to do?

Thanks