html代码如下：

现在是<span id="TimeSpan"></span>

<script type="text/javascript">
                                    ShowTime();
                                </script>

Js脚本

<script type="text/javascript">
        function ShowTime() {
            now = new Date();
            hour = now.getHours();
            minute = now.getMinutes();
            second = now.getSeconds();
            var day = ["日", "一", "二", "三", "四", "五", "六", ];
            time_str = (hour < 10) ? ("0" + hour) : hour;
            time_str += ":";
            time_str += (minute < 10) ? ("0" + minute) : minute;
            time_str += ":";
            time_str += (second < 10) ? ("0" + second) : second;
            $$("TimeSpan").innerHTML = "" + (now.getFullYear()) + "年" + (now.getMonth() + 1) + "月" + (now.getDate() + 0) + "日 " + time_str + " 星期" + day[new Date().getDay()];
            setTimeout('ShowTime()', 1000);
        }

</script>