jqGrid 选中行不选中icheck 阻止事件

beforeSelectRow: function (rowid, e) { 
      var $myGrid = $(this), 
          i = $.jgrid.getCellIndex($(e.target).closest('td')[0]), 
          cm = $myGrid.jqGrid('getGridParam','colModel'); 
      return (cm[i].name ==='cb'); 
  }