Office.js当前不支持此事件.同时，我建议公开一个按钮，使用户可以将文档显式地保存在LOB中，无论是在功能区中还是在加载项本身中.

this event is currently not supported in Office.js. I recommend in the meantime to expose a button to make the user explicitly save the document on the LOB, either in the ribbon or in the add-in itself.