有趣的是，从伸缩性的观点来看，它限制了服务器端的缓存大小。

From a scalability point of view it's interesting to limit the size of the server side cache.

youdao

至于跨域的限制，跨文档进行消息传输的API非常有趣的允许跨源(cross - origin)通信，但是开发者需要非常小心的使用它，在任何时候确保安全性。

About cross-domain limitation, the cross Document Messaging API is interesting to allow cross-origin communication but the developer as to be very careful using it and ensure security at all time.

youdao