Set Custom Field Values From Due Date

gistfile1.txt

function setCustomFieldValuesFromDueDate(notification)
{
  //Will trigger for adding or editing a due date 
  var card = new Notification(notification).addedDueDate();
  //Set these offsets accordingly. The element name is the
  //name of the field (eg. production stage) and the value
  //is offset in days, plus or minus
  var offsets = {"Field 1": -1,
                 "Field 2": -3,
                 "Field 3": -7};
                 
  new IterableCollection(offsets).each(function(value,key)
  {
    //This will create fields as text type if they
    //don't exist, and enable the power up if not enabled.
    //If you want to use these as dates later, make sure the
    //fields already exist before running the function as Date
    //types
    card.setCustomFieldValue(key,new Date(card.due()).addDays(value));
  });
}