code: function isDayBefore(d1, d2) {
    var day1 = clone(d1).setHours(0, 0, 0, 0);
    var day2 = clone(d2).setHours(0, 0, 0, 0);
    return day1 < day2;
  }
docs: Returns `true` if the first day is before the second day.
  
  @export
  @param {Date} d1
  @param {Date} d2
  @returns {Boolean}