User-Agent JS Fixer

This addon can change the JavaScript User-Agent on a per-site basis, rather than changing for the whole session.
It does nothing by itself, but it complements the functionality of another addon like UAControl or ua-site-switch. No additional configuration is required, it uses the same settings from them.

All it does is to redefine the User-Agent for JavaScript code (navigator.userAgent) using the same string that was sent on the HTTP header.

Any website where you enable javascript can see right through your fake because this add-on does not cover the navigator.oscpu part of the user agent.