I need to exclude the days of Christmas and New Year

Been following your post, they are very good.

I need your help.

There is an arrangement that I used to find it in the Podium group. I found it very good.

var startDate = @Days/time out office
var endDate = @Return to office

function workingDaysBetweenDates(startDate, endDate) {

// Validate input
if (endDate < startDate)
return 0;

// Calculate days between dates
var millisecondsPerDay = 86400 * 1000; // Day in milliseconds
startDate.setHours(0,0,0,1); // Start just after midnight
endDate.setHours(23,59,59,999); // End just before midnight
var diff = endDate - startDate; // Milliseconds between datetime objects
var days = Math.ceil(diff / millisecondsPerDay);

// Subtract two weekend days for every week in between
var weeks = Math.floor(days / 7);
var days = days - (weeks * 2);

// Handle special cases
var startDay = startDate.getDay();
var endDay = endDate.getDay();

// Remove weekend not previously removed.
if (startDay - endDay > 1)
days = days - 2;

// Remove start day if span starts on Sunday but ends before Saturday
if (startDay == 0 && endDay != 6)
days = days - 1

// Remove end day if span ends on Saturday but starts after Sunday
if (endDay == 6 && startDay != 0)
days = days - 1

return days;
}
startDate == null || endDate == null ? "" : workingDaysBetweenDates( new Date(startDate) , new Date(endDate))

But now I need to exclude the days of Christmas and New Year. I send you the code, it doesn't work for me :-(
I found this code, but there is something that does not work for me, I assigned a field

var startDate = @Days/time out office
var endDate = @Return to office
var holidays = @Christmas

function workingDaysBetweenDates(startDate, endDate) {

// Validate input
if (endDate < startDate)
return 0;

// Calculate days between dates
var millisecondsPerDay = 86400 * 1000; // Day in milliseconds
startDate.setHours(0,0,0,1); // Start just after midnight
endDate.setHours(23,59,59,999); // End just before midnight
var diff = endDate - startDate; // Milliseconds between datetime objects
var days = Math.ceil(diff / millisecondsPerDay);

// Subtract two weekend days for every week in between
var weeks = Math.floor(days / 7);
var days = days - (weeks * 2);

// Handle special cases
var startDay = startDate.getDay();
var endDay = endDate.getDay();

// Remove weekend not previously removed.
if (startDay - endDay > 1)
days = days - 2;

// Remove start day if span starts on Sunday but ends before Saturday
if (startDay == 0 && endDay != 6)
days = days - 1

// Remove end day if span ends on Saturday but starts after Sunday
if (endDay == 6 && startDay != 0)
days = days - 1

// Remove end day if span ends on Saturday but starts after Sunday
if (endDay == 6 && startDay != 0)
days = days - 1

// Check for Holiday in range --
for (var i in holidays) {
if ((getDiffDay(holidays[i], startDate) >= 0) && ( getDiffDay(holidays[i] , endDate) <= 0 )) {
days--;

return days;
}
startDate == null || endDate == null ? "" : workingDaysBetweenDates( new Date(startDate) , new Date(endDate))

Thanks very much,

Katherine