Echarts中地图引用问题

npm ls echarts  // 查看自己的echarts版本
npm install echarts@4.1.0 --save  //下载低版本echats包含china.js

import "echarts/map/js/china.js";

import chinaMap from "@/assets/echarts/china.json";
mounted() {
  echarts.registerMap("china", { geoJSON: chinaMap });
  if (!this.chart) {
    this.chart = echarts.init(this.$el)
  }

  let option = {
        geo:{
            map:'china',
        }
  }
  this.chart.setOption(option);
},

import "@/assets/echarts/china.js";