Add layerName and layers options to ol.source.TopoJSON

externs/olx.js

@@ -2040,7 +2040,11 @@ olx.format.PolylineOptions.prototype.geometryLayout;
 
 
 /**
- * @typedef {{defaultDataProjection: ol.ProjectionLike}}
+ * @typedef {{
+ *     defaultDataProjection: ol.ProjectionLike,
+ *     layerName: (string|undefined),
+ *     layers: (Array.<string>|undefined)
+ * }}
  */
 olx.format.TopoJSONOptions;
 
@@ -2053,6 +2057,38 @@ olx.format.TopoJSONOptions;
 olx.format.TopoJSONOptions.prototype.defaultDataProjection;
 
 
+/**
+ * Set the name of the TopoJSON topology `objects`'s children as feature
+ * property with the specified name. This means that when set to `'layer'`, a
+ * topology like
+ * ```
+ * {
+ *   "type": "Topology",
+ *   "objects": {
+ *     "example": {
+ *       "type": "GeometryCollection",
+ *       "geometries": []
+ *     }
+ *   }
+ * }
+ * ```
+ * will result in features that have a property `'layer'` set to `'example'`.
+ * When not set, no property will be added to features.
+ * @type {string|undefined}
+ * @api
+ */
+olx.format.TopoJSONOptions.prototype.layerName;
+
+
+/**
+ * Names of the TopoJSON topology's `objects`'s children to read features from.
+ * If not provided, features will be read from all children.
+ * @type {Array.<string>|undefined}
+ * @api
+ */
+olx.format.TopoJSONOptions.prototype.layers;
+
+
 /**
  * @typedef {{altitudeMode: (ol.format.IGCZ|undefined)}}
  */