How to validate a selected date in Jquery ?

Question

Hi ,
i'm new to jquery.In my application am using a date picker.can anyone tell me,How to validate a selected date in Jquery.
the condition is that after user select a date
it will validate that the date is current date or yesterday date.other than this will show error message.if yesterday is saturday or sunday(i.e holiday) then
user should allow to select friday.