arcgis api 3.x使用typescript

npm install --save @types/arcgis-js-api@3

使用方法：

 loadModules(['esri/layers/GraphicsLayer', 'esri/geometry/Polygon', 'esri/graphic', 'esri/symbols/SimpleFillSymbol', 'esri/symbols/SimpleLineSymbol', 'esri/Color']).then(res => {
                const [GraphicsLayer, Polygon, Graphic, SimpleFillSymbol, SimpleLineSymbol, Color] = res as MapModules;
                const layer = new GraphicsLayer({ id: 'townsLayer' });
               

                var polygonSymbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID, new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID, new Color([39, 209, 155, 0.8]), 3), new Color([151, 249, 0, 0]));
                townsData.features.forEach(item => {
                    const { properties, geometry } = item;
                    const { coordinates } = geometry;

                    var polygonJson = {
                        rings: coordinates,
                        spatialReference: { wkid: 4490 },
                    };
                    var polygon = new Polygon(polygonJson);
                    const graphic = new Graphic(polygon, polygonSymbol, properties);
                    layer.add(graphic);
                });
                map.addLayer(layer);