尝试更改您的 fnRowCallback 到以下内容：

Try changing your fnRowCallback to the following:

"fnRowCallback": function( nRow, aData, iDisplayIndex ) {
  nRow.className = "gradeX odd";
  return nRow;
}

您可以参考正式文档以进一步了解此回调函数。

You can refer to the offical documentation to further understanding this callback function.