Q:

How to expire a Cookie using Jquery at midnight?

I did this:
$.cookie("ultOS", (i), {expires:1});

But it will only expire next day.
How can I expire a cookie at midnight?
Would this work instead?
var date = new Date();
var midnight = new Date(date.getFullYear(), date.getMonth(), date.getDate(), 23, 59, 59);
$.cookie("ultOS", (i), {expires: midnight});

A:

I think this would work:
var currentDate = new Date();
expirationDate = new Date(currentDate.getFullYear(), currentDate.getMonth(), currentDate.getDate()+1, 0, 0, 0);
$.cookie("ultOS", "5", {expires: expirationDate});

A:

According to the latest version of ths cookie plugin (assuming this is the one you're using: http://plugins.jquery.com/project/Cookie), you can pass a normal Date object in.  
I haven't tried it, but the source of the plugin is fairly straightforward....
if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) {
            var date;
            if (typeof options.expires == 'number') {
                date = new Date();
                date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
            } else {
                date = options.expires;
            }
            expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
        }

If you pass in a number, it assumes that's number of days.  If you pass in a Date, it takes that.

