鼠标触上去出现小圆框

描述:当前是关于Echarts图表中的 折线图 示例。
 
            let myData5 = [
        "1月",
        "2月",
        "3月",
        "4月",
        "5月",
        "6月",
        "7月",
        "8月",
        "9月",
        "10月",
        "11月",
        "12月",
      ];
      let ht = [
        1100, 1200, 800, 900, 1000, 400, 500, 1200, 1150, 800, 1026, 1300,
      ];
      let option = {
        backgroundColor: "#091022",
        tooltip: {
          trigger: "axis",
          axisPointer: {
            lineStyle: {
              color: {
                type: "linear",
                x: 0,
                y: 0,
                x2: 0,
                y2: 1,
                colorStops: [
                  {
                    offset: 0,
                    color: "rgba(0, 255, 233,0)",
                  },
                  {
                    offset: 0.5,
                    color: "rgba(255, 255, 255,1)",
                  },
                  {
                    offset: 1,
                    color: "rgba(0, 255, 233,0)",
                  },
                ],
                global: false,
              },
            },
          },
          textStyle: {
            color: "#fff",
          },
          backgroundColor: "rgba(0, 58, 99, 0.8)", //设置背景颜色
          borderColor: "rgba(0, 58, 99, 0.8)",
          confine: true,
          formatter: "{b}:{c}份合同",
        },
        legend: {
          // icon: "rect",
          itemWidth: 20,
          itemHeight: 10,
          itemGap: 20,
          right: "4%",
          top: "2%",
          textStyle: {
            fontSize: 14,
            color: "#fff",
          },
          data: ["合同数量"],
          selectedMode: false,
        },
        grid: {
          top: "14%",
          left: "2%",
          right: "4%",
          bottom: "2%",
          containLabel: true,
        },
        xAxis: {
          type: "category",
          data: myData5,
          axisLabel: {
            color: "#A4A7AA",
            interval: 0,
            fontSize: 12,
          },
          axisLine: {
            show: true,
            lineStyle: {
              color: "rgba(127, 214, 255, .4)",
            },
          },
          splitLine: {
            show: false,
          },
          axisTick: {
            show: false,
          },
          boundaryGap: false,
        },
        yAxis: {
          type: "value",
          name: "",
          nameTextStyle: {
            color: "#A4A7AA",
            fontSize: 12,
          },
          axisLine: {
            show: false,
            lineStyle: {
              color: "rgba(127, 214, 255, .4)",
            },
          },
          min: 0,
          axisLabel: {
            show: true,
            color: "#A4A7AA",
            fontSize: 12,
          },
          axisTick: {
            show: false,
          },
          splitLine: {
            show: true,
            lineStyle: {
              width: 0.8,
              color: "rgba(127, 214, 255, .4)",
              type: "dashed",
            },
          },
        },
        series: [
          {
            name: "合同数量",
            type: "line",
            showSymbol: false,
            smooth: true,
            // symbolSize: 8,
            lineStyle: {
              normal: {
                color: "#00FFF6",
              },
            },
            itemStyle: {
              color: "#00FFF6",
              borderColor: "#00FFF6",
              borderWidth: 2,
            },
            areaStyle: {
              normal: {
                color: new echarts.graphic.LinearGradient(
                  0,
                  0,
                  0,
                  1,
                  [
                    {
                      offset: 0,
                      color: "rgba(9, 69, 123, 1)",
                    },
                    {
                      offset: 1,
                      color: "rgba(1, 84, 161, 0)",
                    },
                  ],
                  false
                ),
              },
            },
            data: ht, //data.values
          },
        ],
      };