<b>现在是：<span id="thetime"></span></b>

<script type="text/javascript">
var timerID = null;
var timerRunning = false;

function stopclock() {
    if (timerRunning)
        clearTimeout(timerID);
    timerRunning = false;
}
function startclock() {
    stopclock();
    showtime();
}
function showtime() {
    var now = new Date();
    var hours = now.getHours();
    var minutes = now.getMinutes();
    var seconds = now.getSeconds()
    var timeValue = now.getFullYear() + "年" + (now.getMonth() + 1) + "月" + now.getDate() + "日 "
    timeValue += hours
    timeValue += ((minutes < 10) ? ":0" : ":") + minutes
    timeValue += ((seconds < 10) ? ":0" : ":") + seconds

    document.getElementById("thetime").innerHTML = timeValue;
    timerID = setTimeout("showtime()", 1000);
    timerRunning = true;
}
</script>