header field variables/eval

[brian6932]

So one somewhat odd use case I have's that I spoof referers (network.http.referer.spoofSource), and use this web-extension to selectively enable referers on domains that require them. The problem's that I need the override to be using the current hostname, and sometimes this changes on a shared subdomain, e.g. www.google.com/android/find/ & messages.google.com/web/conversations both request signaler-pa.clients6.google.com & signaler-pa.clients4.google.com. These requests are required for the domains to work properly, the response body indicates that the referer's required, and they get 400 status codes. When the right referer's set, it works as expected. I want some way to execute JS to do string generation within the header's replacement, basically just:

globalThis.location.protocol+'//'+globalThis.location.host+'/'