Method of dynamically loading geojson based on Vue+Openlayer

<template>
  <div id="map" style="width: 100vw; height: 100vh"></div>
</template>
<script>
import "ol/ol.css";
import TileLayer from "ol/layer/Tile";
import VectorLayer from "ol/layer/Vector";
import VectorSource from "ol/source/Vector";
import XYZ from "ol/source/XYZ";
import { Map, View, Feature, ol } from "ol";
import { Style, Stroke, Fill } from "ol/style";
import { Polygon, MultiPolygon } from "ol/geom";
 
import areaGeo from "@/assets/chengdu.json";
 
export default {
  data() {
    return {
      map: {},
      areaLayer: {},
    };
  },
  mounted() {
    this.initMap(); //Initialize the map method this.addArea(areaGeo); //Add area layer method this.pointMove();
    this.getFeatureByClick();
  },
  methods: {
    pointMove() {
      // Set the style of the mouse over the vector element this.map.on("pointermove", (e) => {
        const isHover = this.map.hasFeatureAtPixel(e.pixel);
        this.map.getTargetElement().style.cursor = isHover ? "pointer" : "";
      });
    },
    getFeatureByClick() {
      this.map.on("click", (e) => {
        let features = this.map.getFeaturesAtPixel(e.pixel);
        this.map.getView().fit(features[0].getGeometry(), {
          duration: 1500,
          padding: [100, 100, 100, 100],
        });
      });
    },
    /**
     * Set area */
    addArea(geo = {}) {
      if (Object.keys(geo).length == 0 && geo.features.length == 0) return;
 
      // Set the layer this.areaLayer = new VectorLayer({
        source: new VectorSource({
          features: [],
        }),
      });
      //Add layer this.map.addLayer(this.areaLayer);
 
      let features = geo.features;
 
      for (let i in features) {
        let areaFeature = {};
 
        if (features[i].geometry.type == "MultiPolygon") {
          areaFeature = new Feature({
            geometry: new MultiPolygon(features[i].geometry.coordinates),
          });
        } else if (features[i].geometry.type == "Polygon") {
          areaFeature = new Feature({
            geometry: new Polygon(features[i].geometry.coordinates),
          });
        }
        areaFeature.setStyle(
          new Style({
            fill: new Fill({ color: "#4e98f444" }),
            stroke: new Stroke({
              width: 3,
              color: [71, 137, 227, 1],
            }),
          })
        );
        areaFeature.setProperties(features[i].properties);
        this.areaLayer.getSource().addFeature(areaFeature);
      }
    },
    /**
     * Initialize the map */
    initMap() {
      this.map = new Map({
        target: "map",
        layers:
          new TileLayer({
            source: new XYZ({
              url: "http://map.geoq.cn/ArcGIS/rest/services/ChinaOnlineStreetPurplishBlue/MapServer/tile/{z}/{y}/{x}",
            }),
          }),
        ],
        view: new View({
          projection: "EPSG:4326",
          center: [103, 31],
          zoom: 7,
        }),
      });
    },
  },
};
</script>