javascript系统时间

<div>
                <%--系统时间--%>
                当前时间是：
                <script type="text/javascript">
                    var week;
                    if (new Date().getDay() == 0) week = "星期日"
                    if (new Date().getDay() == 1) week = "星期一"
                    if (new Date().getDay() == 2) week = "星期二"
                    if (new Date().getDay() == 3) week = "星期三"
                    if (new Date().getDay() == 4) week = "星期四"
                    if (new Date().getDay() == 5) week = "星期五"
                    if (new Date().getDay() == 6) week = "星期六"
                    document.write(new Date().getFullYear() + "年" + (new Date().getMonth() + 1) + "月" + new Date().getDate() + "日 " + week);</script>
                <span id="time"></span>
                <script type="text/javascript">                    setInterval("time.innerHTML=new Date().getHours()+':'+new Date().getMinutes()+':'+new Date().getSeconds()", 1000);</script>
            </div>