Firefox redirect response on xhr request

Suppose we have the xhr 'POST' request that returns 'redirect' status code. In that case browser is sending additional xhr 'GET' by the given URL. I am not sure who is doing that call chain: browser itself or js library(using MooTools).

The problem is that the second 'GET' request is not recognized as xhr by the server: It doesn't have "X-R开发者_JAVA技巧equested-With" header contains "XMLHttpRequest"

The problem appears only on Firefox, but not on Webkit. So, believe it is not related to js library bug.

Does anyone have ideas how to fix it?

The XHR/browser follows redirects internally.

Apparently firefox is not forwarding non-standard headers?

Sound like you should report a bug to BugZilla