弹框内画echarts图dom元素无法获取的问题

弹框内画echarts图dom元素无法获取的问题？ 什么意思呢？就是当我们打开弹框之后，此时要画eachars图，可是echarts图的容器dom此时为null, 因此我们需要做的就是在dom元素获取到后，再去画eachrts图。。。 废话不多说，直接上代码：

html:

<el-dialog title="查看曲线" :visible.sync="dialogCheckEchartsFormVisible">
      <div class="content dialog_con" style="margin-left: 100px">
        <div class="topchart" id="topchart">

        </div>
      </div>
      <div slot="footer" class="dialog-footer">
        <el-button @click="dialogCheckEchartsFormVisible = false" size="mini">关闭</el-button>
      </div>
    </el-dialog>

data定义：

 option : {
          color: ["#f40",'#3398DB'],
          tooltip: {
            trigger: 'axis'
          },
          title: [
            {
              text: '2018年9月电量电费',
              textStyle:{
                fontSize: 16,
                color: "#666"
              },
              x: '45%',
              // subtext:"2018年9月份",
              subtextStyle: {
                fontSize: 12,
                color: "#ccc",
                fontWeight:"bold"
              }
            }
          ],
          legend: {
            data:['电量','电费'],
            right:"80"
          },
          xAxis: {
            type: 'category',
            axisLabel: {
              interval: 0,
              rotate: 75
            },
            /*data: ["北京","天津","蒙东","山西","河北","辽宁","吉林","湖南","湖北","江西","河南","上海","浙江","江苏","山东","安徽","陕西","青海","宁夏","新疆","西藏","四川","重庆"],*/
            data: ["9/1","9/2","9/3","9/4","9/5","9/6","9/7","9/8","9/9","9/10","9/11","9/12","9/13","9/14","9/15",
              "9/16","9/17","9/18","9/19","9/20","9/21","9/22","9/23","9/24","9/25","9/26","9/27","9/28","9/29","9/30"],
            name:"月日"
          },
          yAxis: {
            type: 'value',
            splitNumber:10
          },
          nameTextStyle:{

          },
          series: [
            {
              name:'电量',
              stack: '电量',
              type: 'bar',
              data: [5000, 4900, 4800, 2000, 5500, 1000, 5900,6000,6000,6100,4800,4700,6800,5700,4800,5000, 8000, 4800, 6200, 5500, 4200, 5900,6000,7800,6100,4800,4700,6800,5700,4800],
            },
            {
              name:'电费',
              stack: '电费',
              type: 'bar',
              data: [6000, 5000, 4700, 3000, 6100, 3000, 4900,6100,5100,6000,4900,5800,4800, 5800,5600,6000, 6000, 4700, 6000, 6100, 4800, 4900,6100,9000,6000,4900,5800,4800, 5800,5600],
            }
          ]
        },
        myChart: {},

js:

//查看曲线
      showEcharts(){
        this.dialogCheckEchartsFormVisible=true;
        if(document.getElementById("topchart")){
          this.initchart(
            document.getElementById("topchart"),
            this.option
          );
        }

      },
      initchart(ele, option) {
        this.myChart = this.echarts.init(ele);
        this.myChart.setOption(option);
      },

看似代码没什么问题，但在执行showEcharts方法时会发现dom元素为null,究竟是为什么呢？

原来在于html中控制弹框显示的变量的修饰符.sync,即

sync是异步的，因此正确做法就是将.sync修饰符去掉，如下：

因此就解决了上面所述的问题