moment.js + bootstrap-datetimepicker functions to set an array of holidays

sliding-holidays.js

// requires moment.js
// for use with the datetime picker here https://eonasdan.github.io/bootstrap-datetimepicker

// these functions are meant to calculate the appropriate date for sliding holidays
// for example, Thanksgiving which occurs on the fourth Thursday in November.
// Not necessarily the same date every year.

// left a ton of console.logs so it can be seen in the browser
 
  function getLastOccurringDayOfMonth(startDate,dayOfWeek)
    {
        var dayNumber = moment().day(dayOfWeek).day();
        var found_date = moment(startDate).endOf('month').day(dayNumber);
        // if this is still in the month provided, then return it!
        if (found_date.month() == moment(startDate).month()){

            return found_date;
        }
        var found_date = moment(startDate).endOf('month').subtract(1,'w').day(dayNumber);
        return found_date;

    }

    function getFirstOccurringDayOfMonth(startDate,dayOfWeek)
    {
        var dayNumber = moment().day(dayOfWeek).day();
        var found_date = moment(startDate).startOf('month').day(dayNumber);
        // if this is still in the month provided, then return it!
        if (found_date.month() == moment(startDate).month()){

            return found_date;
        }
        var found_date = found_date.add(1,'w').day(dayNumber);
        return found_date;

    }

    function getSlidingHoliday(startDate,whichWeek,dayOfWeek){
        var dayNumber = moment().day(dayOfWeek).day();
        //console.log('startDate ' + startDate);
       // console.log('day number' + dayNumber);
        var calculatedWeek = whichWeek;
        if (calculatedWeek <= 0){

            var startOfMonth = moment(startDate).utc().startOf('month').startOf('isoweek').allDays(dayNumber);
            return days[calculatedWeek];
        }
        var startOfMonth =  moment(startDate).utc().startOf('month');
       // console.log ( 'start of month day ' + startOfMonth.day());
        if (startOfMonth.day() == dayNumber){
       //     console.log ('appears the start of the month and the requested day name are the same.')
            var appropriate_date = moment(startDate).utc().startOf('month').add(whichWeek -1,'w').day(dayNumber);
       //     console.log('date returned is  ' + appropriate_date.format('YYYY-MM-DD'));
            return appropriate_date;
        }
        if (startOfMonth.day() > dayNumber){
            var weeksToUse = whichWeek-1;
     //       console.log ('start of month after the day number provided.');
            var result = moment(startDate).utc().startOf('month').format('YYYY-MM-DD');

      //      console.log('the start of the month is on ' + result);
            var result = moment(startDate).utc().startOf('month').format('YYYY-MM-DD');
     //       console.log('this should use ' + weeksToUse.toString() + ' instead of  ' + whichWeek.toString());
            var start_of_week = moment(startDate).utc().startOf('month').add(weeksToUse,'w');
            var result =  moment(start_of_week).format('YYYY-MM-DD');
      //      console.log('the appropriate week should be ' + result);
      //      console.log('but we need the next ' + dayOfWeek + ' and this is ' + start_of_week.format('dddd')  );
            var appropriate_date = moment(startDate).utc().startOf('month').add(whichWeek,'w').day(dayNumber);
       //     console.log('so lets get the next monday...' + appropriate_date.format('YYYY-MM-DD'));
            return appropriate_date;
        }
        // if here, then the start of the month is BEFORE the day name provided
        // for example the day name of Monday was provided but the start of the week is on a Sunday.
        var beginningOfMonth =  startOfMonth.format('dddd');
       // console.log(' the beginning of the month is ' + beginningOfMonth + ' and the day needed is ' + dayNumber + ' which is after the start of the month.');
        var appropriate_date = moment(startDate).utc().startOf('month').add(whichWeek - 1,'w').day(dayNumber);
      //  console.log('so lets get the next monday...' + appropriate_date.format('YYYY-MM-DD'));
        return appropriate_date;
    }

    var CurrentYear = moment().year();
    var NextYear = moment().add(1,'y').year();


    function addSlidingHolidayToArray(existingArray, dayPartial, whichWeek, dayName, holidayName){
        var current = getSlidingHoliday(CurrentYear + dayPartial, whichWeek,dayName);
        var next = getSlidingHoliday(NextYear + dayPartial, whichWeek,dayName);
        existingArray.push(current);
        console.log( CurrentYear.toString() + ' ' + holidayName + ' set to ' + current.format('YYYY-MM-DD'));
        existingArray.push(next);
        console.log( NextYear.toString() + ' ' + holidayName + ' set to ' + next.format('YYYY-MM-DD'));
        return existingArray;
    }

    var HolidayDisabledDates = [];
    HolidayDisabledDates = addSlidingHolidayToArray(HolidayDisabledDates,'-01-01',3,'Monday','MLK');
    HolidayDisabledDates = addSlidingHolidayToArray(HolidayDisabledDates,'-02-01',3,'Monday','George Washington Birthday');
    HolidayDisabledDates = addSlidingHolidayToArray(HolidayDisabledDates,'-10-01',2,'Monday','Columbus Day');
    HolidayDisabledDates = addSlidingHolidayToArray(HolidayDisabledDates,'-11-01',4,'Thursday','Thanksgiving Day');


    var MemorialDayCurrent = getLastOccurringDayOfMonth(CurrentYear + '-05-01','Monday','Memorial Day');
    var LaborDayCurrent = getFirstOccurringDayOfMonth(CurrentYear + '-09-01','Monday');
    var MemorialDayNext = getLastOccurringDayOfMonth(NextYear + '-05-01','Monday');
    var LaborDayNext = getFirstOccurringDayOfMonth(NextYear + '-09-01','Monday');

    HolidayDisabledDates.push(MemorialDayCurrent);
    HolidayDisabledDates.push(MemorialDayNext);
    HolidayDisabledDates.push(LaborDayCurrent);
    HolidayDisabledDates.push(LaborDayNext);

    
    // associate this with any textbox that uses the .date-picker class
    if ($('.date-picker')[0]) {
        $('.date-picker').datetimepicker({
            format: 'YYYY-MM-DD',
            minDate: moment().add(1,'days').format('YYYY-MM-DD'),
           disabledDates: HolidayDisabledDates,
            useCurrent:false
        });
    }