Echart设置tooltip: formatter格式

修改前

代码：

tooltip: {
  trigger: 'axis',
  formatter: function (params) {
    //console.log(params.length);
    let returnData = "";
    for (let i=0;i<params.length;i++){
      if (params[i].seriesName!=""){
        let indexColor = params[i].color;
        returnData += '<span style="display:inline-block;margin-right:5px;border-radius:10px;width:9px;height:9px;background:'+ indexColor +'"></span>';
        returnData += params[i].seriesName +":" + params[i].value + "</br>";
      }
    }
    return returnData;
  }
},

修改后