//获得某月的最后一天          function getLastDay(year,month) {                      var new_year = year;    //取当前的年份                       var new_month = month++;//取下一个月的第一天，方便计算（最后一天不固定）                       if(month>12) {                       new_month -=12;        //月份减                        new_year++;            //年份增                       }                      var new_date = new Date(new_year,new_month,1);                //取当年当月中的第一天                       return (new Date(new_date.getTime()-1000*60*60*24)).getDate();//获取当月最后一天日期                  }