如何使用Javascript取得距今n天前的日期_javascript技巧

複製程式碼如下程式碼：

 function Test(day );
                var beforMilliseconds = Today.getTime() - 1000 * 3600 * 24 * ;
                beforday.setTime(beforMillisecond s);
       .getFullYear();
                var strDay = beforday.getDate();
                   if (strMonth              
                }
                    alert(strYesterday);
            }