js显示yyyy年mm日dd天 星期几 的格式日期

js代码：

     <script type="text/javascript">
         var today = new Date();
         var week; //存储星期几
         var date; //存储日期
         switch (today.getDay()) {
             case 0:
                 week = "星期日";
                 break;
             case 1:
                 week = "星期一";
                 break;
             case 2:
                 week = "星期三";
                 break;
             case 3:
                 week = "星期日";
                 break;
             case 4:
                 week = "星期四";
                 break;
             case 5:
                 week = "星期五";
                 break;
             case 6:
                 week = "星期六";
                 break;
             default:
                 week = "未知";
                 break;
         }
         date = (today.getFullYear()) + "年" + (today.getMonth() + 1) + "月" + today.getDate() + "日" + " ";
         document.write(date + week);  //将日期打印到body
     </script>