Datepicker: isDisabledDate: Check if a given date is currently disabled.

For a project I'm working on I needed the ability to ask and answer the question "Is this date currently disabled in the datepicker?" for a specific date. I have not been able to find any built in way to do this by looking at the source, reading the documentation or searching google. If there is I apologize (also, what is it?)

In my scenario I have 2-4 datepickers on a page all of which have custom disabled dates as well as possibly minDate and maxDate and any of these datepickers may have the min and max dates may change after initialization. Tracking all of this separately makes no sense to me since the datepickers already track it anyway.

My crude solution is below. It's pretty much ripped from _generateHTML() without any attempt to understand how it works or make it nicer. Granted that it might be nicer to overload isDisabled perform this function if given a non-null parameter instead of creating a whole new method.

_isDisabledDateDatepicker: function(target, check_date){
	if(check_date) {
		var inst = $.data(target, PROP_NAME);

		var minDate = this._getMinMaxDate(inst, 'min');
		var maxDate = this._getMinMaxDate(inst, 'max');
		
		var beforeShowDay = this._get(inst, 'beforeShowDay');
		var showCurrentAtPos = this._get(inst, 'showCurrentAtPos');
		var selectOtherMonths = this._get(inst, 'selectOtherMonths');
		var drawMonth = inst.drawMonth - showCurrentAtPos;
		var daySettings = (beforeShowDay ?
			beforeShowDay.apply((inst.input ? inst.input[0] : null), [check_date]) : [true, '']);
		var otherMonth = (check_date.getMonth() != drawMonth);

		var unselectable = (otherMonth && !selectOtherMonths) || !daySettings[0] ||
			(minDate && check_date < minDate) || (maxDate && check_date > maxDate);
	
		return unselectable;
	}
	return false;
}

A small modification was obviously also required in $.fn.datepicker to add isDisabledDate to the list of methods.

I expect someone else may need this functionality sooner or later, so there it is.