我不知道是否有一种方法如何检测时的响应从本地缓存返回？可能吗？

I'm wondering if there is a way how to detect when a response is returned from a local cache? Is it possible?

该解决方案应该是全面和无条件的要求工作。在这种情况下，响应code是总是200行，但XHR返回一个高速缓存资源的第二请求（例如，第一响应包含Expires头，所以没有必要请求服务器的新资源期满之前日期）。

The solution should be general and work for unconditional requests. In this case, the response code is always 200 OK, but XHR returns a cached resource for the second request (e.g. the first response contains Expires header, so there is no need to ask a server for a new resource before the expiration date).

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答案是日期标题

例如。