js顯示yyyy年mm日dd天 星期幾 的格式日期

<script type="text/javascript">
    var today = new Date();
    var week; //存儲星期幾
    var date; //存儲日期
    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);  //將日期打印到body
</script>