How Do I Create A Countdown Time That Resets At A Specific Time
===

Let me first say I do not have a deep understanding of javascript but I know how to work my way around enough to write small scripts for pages.  A client of mine needs me to do the following for a website:

a) Find the user's local time on their computer.
b) Take that local time and subtract it from 6pm.
c) Display that time in a countdown or just a statement letting the user know how much time is left for same day shipping.
d) After 6pm the time resets or disappears until the next business day.

So far I've been able to create the logic for getting the time from the local computer.  I thought I'd be able to use datejs but it does not calculate hours in a day.

Here is the current code I have:

    var currentTime = new Date()
    var hours = currentTime.getHours()
    var minutes = currentTime.getMinutes()

    var suffix = "AM";
    if (hours >= 12) {
    suffix = "PM";
    hours = hours - 12;
      }
    var suffix = "AM";
    if (hours >= 12) {
    suffix = "PM"; 
    hours = hours - 12;
    }
    if (hours == 0) {
    hours = 12;
    }
    if (minutes < 10)
    minutes = "0" + minutes
    document.write("<b>" + hours + ":" + minutes + " " + suffix + "</b>")