如何将rings数组转换为GeoJSON对象，使用ArcGIS Geometry类实现

你之前操作失败的核心原因是Geometry是ArcGIS JS API中的抽象基类，不可直接实例化，你持有的rings属于多边形坐标环，需使用Polygon子类完成实例化后再转换，具体操作如下：

4.x版本API实现步骤 #

1. 引入依赖模块

import Polygon from "@arcgis/core/geometry/Polygon";
import * as webMercatorUtils from "@arcgis/core/geometry/support/webMercatorUtils";
import { geojsonUtils } from "@arcgis/core/geometry/support/geojsonUtils.js";

2. 声明rings数组

const rings = [
    [-13441425.32511117, 4491520.711015136],
    [-13440894.1920939, 4491511.685098792],
    [-13440922.71925878, 4490494.010447212],
    [-13441438.25014971, 4490494.010447212],
    [-13441425.32511117, 4491520.711015136]
];

3. 创建多边形实例
   注意单个坐标环需要包裹一层外层数组，符合Polygon的rings参数格式要求

const polygon = new Polygon({
    rings: [rings],
    spatialReference: { wkid: 3857 }
});

4. 转换为GeoJSON对象
   如果需要输出符合标准规范的WGS84坐标系GeoJSON，可以先做坐标转换：

// Web墨卡托转WGS84
const wgs84Polygon = webMercatorUtils.webMercatorToGeographic(polygon);
// 生成GeoJSON对象
const geoJson = geojsonUtils.fromGeometry(wgs84Polygon);

如果不需要转换坐标系，直接传入原多边形实例即可。

3.x版本API实现步骤 #

require([
    "esri/geometry/Polygon",
    "esri/SpatialReference",
    "esri/geometry/webMercatorUtils",
    "esri/geometry/geojsonUtils"
], function(Polygon, SpatialReference, webMercatorUtils, geojsonUtils) {
    const rings = [
        [-13441425.32511117, 4491520.711015136],
        [-13440894.1920939, 4491511.685098792],
        [-13440922.71925878, 4490494.010447212],
        [-13441438.25014971, 4490494.010447212],
        [-13441425.32511117, 4491520.711015136]
    ];
    const polygon = new Polygon(new SpatialReference(3857));
    polygon.addRing(rings);
    // 坐标转WGS84（可选）
    const wgs84Polygon = webMercatorUtils.webMercatorToGeographic(polygon);
    // 转GeoJSON
    const geoJson = geojsonUtils.toGeoJson(wgs84Polygon);
});

内容的提问来源于stack exchange，提问作者sushifl0p