regex.js

var $time = $('#details time'),
    iso = /^(\d{4}|[+\-]\d{6})-(\d{2})(?:[T ](\d{2}):(\d{2})(?::(\d{2})(?:\.(\d{3,}))?)?(?:(Z)|([+\-])(\d{2})(?::?(\d{2}))?))?/;
    parse = function (date) {
    	var timestamp = Date.parse (date),
    	    minutesOffset = 0,
    	    s;

    	if (isNaN (timestamp) && (s = iso.exec (date))) {
    		if (s[8] !== 'Z') {
    			minutesOffset = +s[10] * 6- + (+s[11]);

    			if (s[9] === '+')
    				minutesOffset = 0 - minutesOffset;
    		}

    		timestamp = Date.UTC (+s[1], +s[2] - 1, +s[3], +s[4], +s[5] + minutesOffset, +s[6], +s[7].substr (0, 3));
    	}

    	return timestamp;
    },
    endTime = parse ($time.attr ('datetime')),
    tick = function () {
    	var now = new Date (),
    	    utcNow = new Date (now.getUTCFullYear (), now.getUTCMonth (), now.getUTCDate (), now.getUTCHours (), now.getUTCMinutes (), now.getUTCSeconds (), now.getUTCMilliseconds ()),

    	    remaining = parseInt ((endTime - utcNow) / 1000),
    	    seconds = remaining % 60,

    	    minutesLeft = parseInt (remaining / 60),
    	    minutes = minutesLeft % 60,

    	    hoursLeft = parseInt (minutes / 60),
    	    hours = hoursLeft % 24,

    	    daysLeft = parseInt (hoursLeft / 24);

    	if (remaining <= 0) {
    		$time.html ('Time\'s up! This deal is over.');
    		$time.show ();
    		clearInterval (countdownIntervalId);
    		return;
    	}

    	if (seconds < 10)
    		seconds = '0' + seconds;

    	if (minutes < 10)
    		minutes = '0' + minutes;

    	$time.html ((daysLeft > 0 ? daysLeft + ' day' + (daysLeft > 1 ? 's' : '') + ', ' : '') + hours + ':' + minutes + ':' + seconds);
    	$time.show ();
    },
    countdownIntervalId = setInterval (tick, 1000);