JQuery UI Datepicker with beforeShowDay function

Question

I am relatively new to JavaScript and JQuery. I wanted a Datepicker that has the following functionality:

1. Weekends are not selectable
2. Non working days (bank holidays etc.) are not selectable
3. The first selectable day must be x number of full working days in the future, taking into account bank holidays and weekends

I looked at few examples and came up with this (the date format is dd/mm):

$(function() {
 var holidays= [[3,1], [22,4], [25,4], [29,4], [2,5], [30,5], [29,8], [26,12], [27,12]];
 var workingDayOffset = 10, selectedDate = new Date();
 function nonWorkingDays(date) {
 for (var j = 0; j < holidays.length; j++) {
 if (date.getMonth() == holidays[j][1] - 1 && date.getDate() == holidays[j][0]) {
 return [false, ''];
 }
 }
 return [true, ''];
 }
 function beforeCurrentDate(date) { 
 if(date.getDate() === selectedDate.getDate() && date.getMonth() === selectedDate.getMonth() && date.getFullYear() === selectedDate.getFullYear())
 {
 return [true, ''];
 } 
 return [date < selectedDate,'']; 
 }
 function nonAvailableDays(date) {
 var noWeekend = $.datepicker.noWeekends(date), before = beforeCurrentDate(date), holiday = nonWorkingDays(date); 
 return [noWeekend[0] && before[0] && holiday[0], ''];
 }
 for(var i = 0; i < workingDayOffset; i++) {
 selectedDate.setDate(selectedDate.getDate() + 1);
 if(!nonAvailableDays(selectedDate)[0])
 { 
 i--;
 } 
 }
 Date.prototype.formatDDMMYY=function(){
 var dd = this.getDate(), mm = this.getMonth()+1, yyyy = this.getFullYear();
 if(dd<10){
 dd = '0' + dd;
 } 
 if(mm<10){
 mm = '0'+ mm;
 }
 return String(dd + "\/" + mm + "\/" + yyyy);
 };
 $( "#datepicker" ).val(selectedDate.formatDDMMYY());
 $( "#datepicker" ).datepicker({ beforeShowDay: nonAvailableDays, dateFormat: 'dd/mm/yy', showOn: 'button', buttonText: "select", defaultDate: selectedDate,gotoCurrent: true}) ; 
});

I am looking for a general critique of the code, but also there are a couple of things that I thought would be easier / cleaner:

1. In beforeCurrentDate I wanted to do a check that the date was less than selectedDate, in terms of the whole date, not including the time component. Using date > selectedDate would return false even if the date component was the same, due to the time part. I thought about setting the time on the selected date, but then GMT offset came into play. It seemed to me that it should be easier, in the end I added a fudge that check just the date components for a match.

2. I am not sure adding Date.prototype.formatDDMMYY is the right way to go. Again, this felt like it should be more straight forward.

I am interested to hear your thoughts on this.

Answer 1

for 1)

var today = new Date();
today.setTime(0); // resets the time. (midnight)

I believe this will fix the date comparison issue

for 2)

It just sucks that there isn't a built-in for this sort of thing. I would suggest not putting it on the Date prototype just in case it conflicts with some other date function/library down the road. Its seems to be only a matter of preference though.

(if you Google: JavaScript format date you'll see many other examples of formatting the date or https://stackoverflow.com/q/1056728/684890 where there are a few alternatives suggested in case you want some more functionality. )