setDueBasedOnCustomField

gistfile1.txt

var datefieldname = "My Date Field";//update to the name of your actual field
var target_list = "My List";//update to the name of your actual list

////DON'T EDIT BELOW THIS LINE////
var changed = new Notification(notification).changedCustomField();

if(changed.name() == datefieldname)
{
  Card.create(
    changed.card().board().list(target_list),
    changed.card().name()
  ).setDue(changed.value());
}