Set holidays is a fantastic function.
But maybe sometimes we need a function like unset holidays.
It means we still work on Saturday or Sunday, as a return, off work on Monday. In this case, we need unset Saturday, Sunday holidays and set Monday as holiday. 
Hi,
to set Monday as a holiday you may use:
dhtmlxCalendarObject(‘dhtmlxCalendar’, true, {weekend:[1]});
And the following code unsets all holidays
dhtmlxCalendarObject(‘dhtmlxCalendar’, true, {weekend:[]});
setHolidays can be used to set a certain day as a holiday