更新前端静态网页获取方式，放弃使用后端获取api

frontend/node_modules/workbox-background-sync/index.js

@@ -0,0 +1,16 @@
+/*
+  Copyright 2018 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import { BackgroundSyncPlugin } from './BackgroundSyncPlugin.js';
+import { Queue } from './Queue.js';
+import { QueueStore } from './QueueStore.js';
+import { StorableRequest } from './StorableRequest.js';
+import './_version.js';
+/**
+ * @module workbox-background-sync
+ */
+export { BackgroundSyncPlugin, Queue, QueueStore, StorableRequest };