diff --git a/js/src/mapapi/api_gmaps.js b/js/src/mapapi/api_gmaps.js
index 3b0a059..df5c700 100644
--- a/js/src/mapapi/api_gmaps.js
+++ b/js/src/mapapi/api_gmaps.js
@@ -443,6 +443,9 @@ export default class GoogleMapsApi {
     }
     return null;
   }
+
+  // eslint-disable-next-line class-methods-use-this
+  saveState() {/* empty */}
 }
 
 /** @type {boolean} */
diff --git a/js/src/mapapi/api_openlayers.js b/js/src/mapapi/api_openlayers.js
index 7d1ad43..56cb3bd 100644
--- a/js/src/mapapi/api_openlayers.js
+++ b/js/src/mapapi/api_openlayers.js
@@ -777,6 +777,9 @@ export default class OpenLayersApi {
     }
     return null;
   }
+
+  // eslint-disable-next-line class-methods-use-this
+  saveState() {/* empty */}
 }
 /** @type {number} */
 OpenLayersApi.ZOOM_MAX = 20;