<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>网页倒计时</title>
<script language="JavaScript"> 
<!-- hide script from old browser
    var DifferenceHour = -1
    var DifferenceMinute = -1
    var DifferenceSecond = -1
    var Tday = new Date("Aug 27, 2014 20:00:00")   //**倒计时时间点-注意格式
    var daysms = 24 * 60 * 60 * 1000
    var hoursms = 60 * 60 * 1000
    var Secondms = 60 * 1000
    var microsecond = 1000
    function clock() {
        var time = new Date()
        var hour = time.getHours()
        var minute = time.getMinutes()
        var second = time.getSeconds()
        var timevalue = "" + ((hour > 12) ? hour - 12 : hour)
        timevalue += ((minute < 10) ? ":0" : ":") + minute
        timevalue += ((second < 10) ? ":0" : ":") + second
        timevalue += ((hour > 12) ? " PM" : " AM")
        var convertHour = DifferenceHour
        var convertMinute = DifferenceMinute
        var convertSecond = DifferenceSecond
        var Diffms = Tday.getTime() - time.getTime()
        DifferenceHour = Math.floor(Diffms / daysms)
        Diffms -= DifferenceHour * daysms
        DifferenceMinute = Math.floor(Diffms / hoursms)
        Diffms -= DifferenceMinute * hoursms
        DifferenceSecond = Math.floor(Diffms / Secondms)
        Diffms -= DifferenceSecond * Secondms
        var dSecs = Math.floor(Diffms / microsecond)
        if (convertHour != DifferenceHour) document.formnow.dd.value = DifferenceHour
        if (convertMinute != DifferenceMinute) document.formnow.hh.value = DifferenceMinute
        if (convertSecond != DifferenceSecond) document.formnow.mm.value = DifferenceSecond
        document.formnow.ss.value = dSecs
        setTimeout("clock()", 1000)
    }
    // end hiding --> 
</script>
</head>

<body onload="clock();return true">

倒计时：<br>
<form name="formnow">
 <input name="dd" type="text" style="border:0;" size="2"> 天 
 <input name="hh" type="text" style="border:0;" size="2"> 小时 
 <input name="mm" type="text" style="border:0;" size="2"> 分 
 <input name="ss" type="text" style="border:0;" size="2"> 秒 
</form>
</body>
</html>