Is it possible to change a specific day of week only?

[chrcorn]

I need to be able to pick only the fridays on the calendar. is it possible?

[dangrossman]

Yes:

$('#element').daterangepicker({ 
  isInvalidDate: function(date) {
    //return true for all days of week except friday
    return date.day() != 5;
  } 
});