Zim提出了一个问题：Prevent redirection of Xmlhttprequest，或许与您遇到的问题类似。
Not according to the W3C standard for the XMLHttpRequest object(emphasis added):
If the response is an HTTP redirect:
If the origin of the URL conveyed by the Location header is same origin with the XMLHttpRequest origin and the redirect does not violate infinite loop precautions, transparently follow the redirectwhile observing the same-origin request event rules.
They were consideringit for a future release:
This specification does not include the following features which are being considered for a future version of this specification:
- Property to disable following redirects;
but the latestspecification no longer mentions this.