js 要求传入两个日期时间，返回两个日期时间之间，相差多少天多少小时多少分钟多少秒...

计算两个日期相差多少天多少小时多少分钟多少秒

function dateDiff(d1,d2){
        var date1 = new Date(d1);
        if(d2){
            var date2 = new Date(d2);
        }else{
            var date2 = new Date();
        }
        var ms = Math.abs(date1.getTime() - date2.getTime());
        var hm=1000;
        var mi=hm*60;
        var hh=mi*60;
        var dd=hh*24;
        var day=parseInt(ms/dd);
        var hour= (ms-day*dd)/hh;
        var minute = (ms - day * dd - hour * hh) / mi;  
        var second = (ms - day * dd - hour * hh - minute * mi) / hm;  
        var milliSecond = ms - day * dd - hour * hh - minute * mi - second * hm; 
        return day+"天"+hour+"小时"+minute+"分钟"+second+"秒"+milliSecond+"毫秒"
    }

    console.log( dateDiff("2008.8.8","2008/7/8"));
    console.log(dateDiff("2020.6.9")) ;