数据源;https://geo.datav.aliyun.com/areas_v3/bound/100000_full.json

// 判断点是否在多边形（外环/内洞）内
function isPointInPolygon(point, polygon) {
    const [outerRing, ...holes] = polygon; // 外环和内洞
    const isInOuterRing = isPointInRing(point, outerRing);

    if (!isInOuterRing) return false; // 点不在外环内，直接返回 false

    // 判断点是否在内洞内
    for (const hole of holes) {
        if (isPointInRing(point, hole)) {
            return false; // 点在内洞内，返回 false
        }
    }

    return true; // 点在外环内且不在任何内洞内
}

// 判断点是否在一个环（简单多边形）内
function isPointInRing(point, ring) {
    const x = point.lng;
    const y = point.lat;
    let isInside = false;

    for (let i = 0, j = ring.length - 1; i < ring.length; j = i++) {
        const xi = ring[i][0], yi = ring[i][1];
        const xj = ring[j][0], yj = ring[j][1];

        const intersect =
            yi > y !== yj > y &&
            x < ((xj - xi) * (y - yi)) / (yj - yi) + xi;
        if (intersect) isInside = !isInside;
    }

    return isInside;
}

// 根据经纬度获取省份（支持 Polygon 类型）
export function getProvinceByCoordinates(point) {
    for (const feature of geoData.features) {
        const { name } = feature.properties;
        const coordinates = feature.geometry.coordinates;

        // Geometry Type 是 Polygon
        if (feature.geometry.type === "Polygon") {
            if (isPointInPolygon(point, coordinates)) {
                return name;
            }
        }

        // Geometry Type 是 MultiPolygon
        if (feature.geometry.type === "MultiPolygon") {
            for (const polygon of coordinates) {
                if (isPointInPolygon(point, polygon)) {
                    return name;
                }
            }
        }
    }
    return null;
}

// 示例数据（你的 GeoJSON 数据）
const geoData = {
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "adcode": 110000,
        "name": "北京市",
        "center": [116.405285, 39.904989],
        "centroid": [116.41995, 40.18994],
        "childrenNum": 16,
        "level": "province",
        "parent": { "adcode": 100000 },
        "subFeatureIndex": 0,
        "acroutes": [100000],
      },
      "geometry": {
        "type": "MultiPolygon",
        "coordinates": [
          [
            [
              [117.348611, 40.581141],
              [117.389879, 40.561593],
              [117.429915, 40.576141],
              [117.412669, 40.605226],
              [117.467487, 40.649738],
              [117.467487, 40.649738],
              [117.501364, 40.636569],
              [117.514914, 40.660181],
              [117.493973, 40.675161],
              [117.408973, 40.686961],
              [117.342451, 40.673799],
              [117.319662, 40.657911],
              [117.278394, 40.664267],
              [117.208177, 40.694675],
              [117.117018, 40.70012],
              [117.11209, 40.707379],
              [117.012308, 40.693767],
              [116.964881, 40.709647],
              [116.926692, 40.745022],
              [116.924229, 40.773581],
              [116.848468, 40.839264],
              [116.81336, 40.848319],
              [116.759773, 40.889954],
              [116.713577, 40.909858],
              [116.722201, 40.927495],
              [116.677853, 40.970888],
              [116.698795, 41.021477],
              [116.688324, 41.044501],
              [116.647672, 41.059394],
              [116.615643, 41.053076],
              [116.623034, 41.021026],
              [116.598397, 40.974503],
              [116.5676, 40.992574],
              [116.519557, 40.98128],
              [116.519557, 40.98128],
              [116.455499, 40.980828],
              [116.447492, 40.953715],
              [116.477057, 40.899907],
              [116.398216, 40.90624],
              [116.370499, 40.94377],
              [116.339702, 40.929303],
              [116.334159, 40.90443],
              [116.438253, 40.81934],
              [116.46597, 40.774487],
              [116.453651, 40.765876],
              [116.316912, 40.772221],
              [116.311369, 40.754996],
              [116.273181, 40.762703],
              [116.247311, 40.791707],
              [116.22021, 40.744115],
              [116.204812, 40.740035],
              [116.171551, 40.695582],
            ],
          ],
        ],
      },
    },
    // 其他省份数据...
  ],
};

// 测试点
const point = { lat: 39.9, lng: 116.4 }; // 北京的经纬度
const province = getProvinceByCoordinates(point, geoData);

console.log(province); // 输出: 北京市

json快捷转ts类型的扩展:https://marketplace.visualstudio.com/items?itemName=GregorBiswanger.json2ts
vscode安装之后 ctrl+alt+V 即可生成类型