This feels like a dumb question, but browsing the API hasn't produced an answer for me yet. I want to get an integer value for the number of days elapsed since a given date. I can create a new Date() object for today, but I can't find a method that will perform a date-date subtraction cleanly. I could use the DAY_OF_YEAR field, but that gets dirty once you start comparing dates from different years. There must be a cleaner way to do this.