echart 下钻与重复渲染，需要清除画布的操作

    if (

        this.echartBar != null &&

        this.echartBar != "" &&

        this.echartBar != undefined

      ) {

        //防止出现图表以渲染警告

        this.echartBar.dispose();

      }

      this.echartBar = echarts.init(document.getElementById("echartEquipment"));

      this.echartBar.clear();