Add method for retrieving ol.Overlay by id

externs/olx.js

@@ -309,7 +309,8 @@ olx.MapOptions.prototype.view;
 
 /**
  * Object literal with config options for the overlay.
- * @typedef {{element: (Element|undefined),
+ * @typedef {{id: (number|string|undefined),
+ *     element: (Element|undefined),
  *     offset: (Array.<number>|undefined),
  *     position: (ol.Coordinate|undefined),
  *     positioning: (ol.OverlayPositioning|string|undefined),
@@ -323,6 +324,15 @@ olx.MapOptions.prototype.view;
 olx.OverlayOptions;
 
 
+/**
+ * Set the overlay id. The overlay id can be used with the
+ * {@link ol.Map#getOverlayById} method.
+ * @type {number|string|undefined}
+ * @api
+ */
+olx.OverlayOptions.prototype.id;
+
+
 /**
  * The overlay element.
  * @type {Element|undefined}