简单的倒计时

<script type="text/javascript">
window.onload = function() {
    var box = document.getElementById('restTime');        
    
    function restTime() {
        var iDay, iHour, iMinute, iSecond;
        var now = new Date(),
        endTime = new Date(2013, 5, 15, 12);
        endTime = (endTime.getTime() - now.getTime()) / 1000;

        iDay = parseInt(endTime/3600/24);
        iHour = parseInt((endTime/3600)%24);
        iMinute = parseInt((endTime/60)%60);
        iSecond = parseInt(endTime%60);

        box.innerHTML = iDay + '天' + iHour + '小时' + iMinute + '分' + iSecond + '秒';

        setTimeout(restTime, 500);
    }

    restTime()
}
</script>