得到CheckBoxList中选中值(checkboxlist动态值)

var res = [];
          var i = 0;
          var attachObj = document.getElementById("cbl_insgdtypeidlist");
          var attachValue = (typeof attachObj.value == 'undefined') ? attachObj.attributes['value'].value : attachObj.value;
          var a = attachValue.split(',');
          while (true) {
              var obj = document.getElementById("cbl_insgdtypeidlist_" + i);
              if (obj == null)
                  break;
              if (obj.checked)
                  res.push(a[i]);
              i = i + 1;
          }

alert(res);//得到选中的值。