echartstool tips多曲线显示数据处理，保留小数位自定义tooltips样式

位置

options=>tooltips=>formatter

 tooltip: {
    trigger: "axis",
    axisPointer: {
      type: "cross",
      label: {
        backgroundColor: "#6a7985",
      },
    },
    formatter:(params)=>{
          console.log(params)
          let str = ''
          params.forEach((element,index) => {
            if(index ===0){
str = element.name + '<br/>'
            }
            let value = element.data
            let name = element.seriesName
            let marker = element.marker
    if(typeof value === 'number'){
      value = value.toFixed(1)
}  
str = str +marker+ name + ":" + value  + '<br/>'    
          });
return str
        }
  },

参照原图写的样式，返回是个数组，数组中包含曲线颜色marker的html，当前点x，y值