JavaScript格式化時間(20080808--->2008-08-08)

/** 格式化日期 **/
        formatDate:function(d){
              if(d==null){
                  d='日期爲空';
                  return d;
              }
              var split= '-';
              if(d == '' || d.length == 10 ){
                    return d;
              }else if(d.length == 6){
                    var data = d.substring(0,4) + split + d.substring(4);
                    return data;
              }else{
                    var data = d.substring(0,4) + split + d.substring(4,6) + split + d.substring(6);
                    return data;
              }
        },