arcgis api for js 3.X版本加载矢量json文件，并缩放至图层

esriLoader.loadModules(
    [
      ‘esri/tasks/FeatureSet‘,
      ‘esri/layers/FeatureLayer‘,
      ‘esri/geometry/Point‘,
      ‘esri/geometry/Polygon‘,
      ‘esri/geometry/Extent‘,
      ‘esri/dijit/PopupTemplate‘,
      ‘esri/dijit/LayerSwipe‘
    ], options).then(
    ([FeatureSet, FeatureLayer, Point, Polygon, Extent, PopupTemplate, LayerSwipe]) => {
　　　　
　　　　//json地址
      const jsonUrl = ‘http://Json/‘ + vectorInfo.label + ‘.json‘

      axios.get(jsonUrl, { headers: {}, emulateJSON: true }).then((res) => {
        const layerJson = res.data

        const layerDefinition = {
          ‘geometryType‘: layerJson.geometryType,
          ‘fields‘: layerJson.fields
        }

        var featureSet = new FeatureSet(layerJson)
        var featureCollection = {
          ‘layerDefinition‘: layerDefinition,
          ‘featureSet‘: featureSet
        }

　　　　//json转成FeatureLayer

　　　　var jsonFeaturelayer = new FeatureLayer(featureCollection) jsonFeaturelayer.id = vectorInfo.vectorId.toString() + ‘_vector‘ 　　　　
　　　　
　　　　//加进图层
        self.map.addLayer(jsonFeaturelayer)
　　　　
　　　　
　　　　//方法一，获取第一个点
        var point = new Point(jsonFeaturelayer._graphicsVal[0]._extent.xmin, jsonFeaturelayer._graphicsVal[0]._extent.ymin)
        self.map.centerAndZoom(point, 8)
　　　　　　
　　　　　　//方法二，所有要素的范围合并
// var mapExtent = new Extent()

        // for (let i = 0; i 
        //   var thisExtent = jsonFeaturelayer._graphicsVal[i].geometry.getExtent()

        //   // 创建范围或先前要素与当前要素的并集
        //   mapExtent = mapExtent.union(thisExtent)
        // }
        // self.map.setExtent(mapExtent)
        // _extent: {xmin: 119.11746198217094, ymin: 36.89781328847772, xmax: 119.2113266911379, ymax: 36.93355761143819,
        // self.map.center = [jsonFeaturelayer._graphicsVal[0]._extent.xmin, jsonFeaturelayer._graphicsVal[0]._extent.ymin]

        // var sGeometry = jsonFeaturelayer.fullExtent
        // var sGeometry = jsonFeaturelayer._graphicsVal[0]._extent
        // var ftGeoExt = sGeometry.getExtent()
        // self.map.setExtent(sGeometry)
      })
    }
  ).catch(err => {
    console.error(err)
  })