记录下vue 中引用echarts 出现 "TypeError: Cannot read property 'getAttribute' of undefined"问题

     <div ref="myChart" style="height:300px;width:100%"></div>

  methods: {
    drawLine() {
      // 基于准备好的dom，初始化echarts实例
      let myChart = this.$echarts.init(this.$refs.myChart);
      // 绘制图表
      myChart.setOption({
        title: { text: "在Vue中使用echarts" },
        tooltip: {},
        xAxis: {
          data: ["衬衫", "羊毛衫", "雪纺衫", "裤子", "高跟鞋", "袜子"]
        },
        yAxis: {},
        series: [
          {
            name: "销量",
            type: "bar",
            data: [5, 20, 36, 10, 10, 20]
          }
        ]
      });
    }
  },
  mounted() {
    this.drawLine();
  }

  mounted() {
    this.$nextTick(() => {
      this.drawLine();
    });
  }