EChart 雷达图显示单点tooltip

最近封装了一个EChart 雷达图方法，效果如图：

代码如下：

/**
 *
 * @param {array} ydata 各方向频率值，暂定8个方向，
 * @param {string} name 名称，
 * @param {string} month 月份，
 * @returns 风玫瑰图option
 */

export async function windRose(ydata, name, month) {
    let newydata
    if (!ydata) {
        newydata = [0, 0, 0, 0, 0, 0, 0, 0]
    } else {
        newydata = ydata[month]
    }
    var max = Math.max(...newydata)
    max = max === 0 ? '1' : max
    const indicator = [{
            name: '北',
            max
        },
        {
            name: 'a',
            max
        },
        {
            name: '西',
            max
        },
        {
            name: 'b',
            max
        },
        {
            name: '南',
            max
        },
        {
            name: 'c',
            max
        },
        {
            name: '东',
            max
        },
        {
            name: 'd',
            max
        },
    ]
    const buildSeries = function (ydata,yname) {
        const data = ydata;
        const helper = data.map((item, index) => {
          const arr = new Array(data.length);
          arr.splice(index, 1, item);
          return arr;
        });
        return [data, ...helper].map((item, index) => {
          return {
            name: yname,
            type: "radar",
            symbol: index === 0 ? "circle" : "none",
            symbolSize: 4,
            itemStyle: {
              color: "#fff",
            },
            lineStyle: {
              color: index === 0 ? "#fac858" : "transparent",
            },
            areaStyle: {
              color: index === 0 ? "#fac858" : "transparent",
              opacity: 0.5,
            },
            tooltip: {
              show: index === 0 ? false : true,
              formatter: () => {
                  let res = indicator[index - 1].name + "：<br>";
              
                  let str =
                    '<i style="display: inline-block;width: 10px;height: 10px;background: ' +
                    "#fac858" +
                    ';margin-right: 5px;border-radius: 50%;}"></i>' +
                    yname +
                    "：" +
                    ydata[index - 1] +
                   '%' +
                    "<br>";
                  res += str;
           
                return res;
              },
            },
            z: index === 0 ? 1 : 2,
            data: [item],
          };
        });
      };
    const series = [];
    series.push(...buildSeries(newydata,name))
    let option = {
        tooltip: {},
        radar: {
          indicator: indicator,
        },
        series: series,
      };
    return option
}