在vue中即使使用v-if依旧无法清除echarts的dom节点，此时我们要用到echarts提供的销毁实例的方法 dispose

<template>
  <div style="padding: 50px;">
    <Button type="primary" @click="switchChat">图表切换</Button>
    <div style="margin-top: 50px;border: 1px solid #eee;padding:30px;">
      <div v-if="isShowPieChat" id="pieChat" style="min-width:900px;height:600px;"></div>
      <div v-else id="lineChat" style="min-width:900px;height:600px;"></div>
    </div>
  </div>
</template>

<script>
import * as echarts from 'echarts';
export default {
  name: "echarts4",
  data() {
    return {
      myPieChat:"",
      myLineChat:"",
      isShowPieChat:true,
    }
  },
  mounted(){
    this.initPieChart();
  },
  methods:{
    initPieChart(){
      this.myPieChat = echarts.init(document.getElementById('pieChat'))
      let option = {
          title: {
            text: 'Referer of a Website',
            subtext: 'Fake Data',
            left: 'center'
          },
          tooltip: {
            trigger: 'item'
          },
          legend: {
            orient: 'vertical',
            left: 'left'
          },
          series: [
            {
              name: 'Access From',
              type: 'pie',
              radius: '50%',
              data: [
                { value: 1048, name: 'Search Engine' },
                { value: 735, name: 'Direct' },
                { value: 580, name: 'Email' },
                { value: 484, name: 'Union Ads' },
                { value: 300, name: 'Video Ads' }
              ],
              emphasis: {
                itemStyle: {
                  shadowBlur: 10,
                  shadowOffsetX: 0,
                  shadowColor: 'rgba(0, 0, 0, 0.5)'
                }
              }
            }
          ]
        };

      option && this.myPieChat.setOption(option);
    },

    initLineChart(){
      this.myLineChat = echarts.init(document.getElementById('lineChat'));
      let option = {
        xAxis: {
          type: 'category',
          data: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
        },
        yAxis: {
          type: 'value',
          axisLine: {     // 是否展示Y轴的竖线，
            show: true,
            lineStyle: {
              color: "black"    // 设置Y轴的颜色
            }
          },
        },
        series: [
          {
            data: [820, 932, 901, 934, 1290, 1330, 1320],
            type: 'line',
            smooth: true
          }
        ]
      };

      option && this.myLineChat.setOption(option);
    },

    switchChat() {
      // 如果直接使用v-if切换的话，不会清除echarts的dom的，当从折线图切换成饼图的时候，会有折线的坐标轴
      this.myPieChat && this.myPieChat.dispose();       // echarts使用dispose方法销毁实例
      this.myLineChat && this.myLineChat.dispose();     // echarts使用dispose方法销毁实例
      this.isShowPieChat = !this.isShowPieChat;
      if(this.isShowPieChat) {
        this.$nextTick(()=>{
          this.initPieChart();
        })
      } else {
        this.$nextTick(()=>{
          this.initLineChart();
        })
      }
    }
  }
}
</script>

<style scoped>

</style>

使用了dispose方法销毁实例