js 获取年月日时分秒星期上下午日期函数

function showtime(){
            let dt=new Date();
            let yy=dt.getFullYear();
            let mm=dt.getMonth()+1;
            let dd=dt.getDate();
            let hh=dt.getHours();
            let mi=dt.getMinutes();
            let ss=dt.getSeconds();
            let dy=dt.getDay();
            let wk="星期"+"日一二三四五六".charAt(dy);
            let sd="上午";
            if(hh>12){
                hh=hh-12;
                sd="下午";
            }
            return yy+"年"+mm+"月"+dd+"日"+"   "+wk+"  "+sd+hh+":"+mi+":"+ss+" ";
        }