如果您的问题不是根据动态数据显示工具提示，则替换以下代码，该工具提示将开始显示-

If your issue is tooltip not showing as per dynamic data then replace the below code, the tooltip will start showing -

    tip.offset([-10, 0]).html(d => {
      return (
        "<strong>Frequency:</strong> <span style='color:red'>" +
         d.train + "</span>"
       );
     });

希望它会对您有所帮助:)

Hope it will help you :)