diff --git a/apps/showcase/doc/tree/selection/SingleDoc.vue b/apps/showcase/doc/tree/selection/SingleDoc.vue
index 9a001ae90..7c3314605 100644
--- a/apps/showcase/doc/tree/selection/SingleDoc.vue
+++ b/apps/showcase/doc/tree/selection/SingleDoc.vue
@@ -33,7 +33,8 @@ import { NodeService } from '@/service/NodeService';
 export default {
     data() {
         return {
-            nodes: null
+            nodes: null,
+            selectedKey: null,
         };
     },
     mounted() {