[Solved] Fetching data cross-domain?

Hi, I’m trying to make an add-on that removes links matching user-supplied criteria/URLs, cross-domain. To do this, it basically requires the add-on to have the ability to crawl pages for content to filter. I thought this would be a fairly simple task, until I ran into CORS. It appears that I am unable to use XHR’s or the Fetch API. The MDN article explains the mechanics of CORS, but offers no alternatives to request pages from foreign domains.

I asked this question in another forum, where I got the response that making the requests from background script instead of a content script could possibly work, but after having tried it it makes no difference.
What options remain?

*facepalm*
Such a silly mistake.
Thanks for pointing me in the right direction