Running uc.js on moz-extension page?

[jathek]

I'm trying to run a simple script on a page created by an add-on but it's not working. Is this possible via userChrome.js? Normally I'd use Tampermonkey for this sort of thing, but that can't run on pages created by other extensions.

// ==UserScript==
// @name           FeedBro - HQ Favicon
// @description    change feedbro favicon to hq
// @include        moz-extension://92d2cbae-768f-469d-b49e-dd4852839ff1/reader.html
// @author         nearcatch
// ==/UserScript==

(function () {
  setTimeout(() => {
    console.log('hi');
    var favicon = document.querySelector('link[href="images/reader16.png"]');
    favicon.setAttribute("href", "images/reader48.png");
  }, 2000);
})();

[xiaoxiaoflood]

You could use something like this:

// ==UserScript==
// @name           test
// @include        main
// ==/UserScript==

window.messageManager.loadFrameScript('data:, (' + function () {
  addEventListener('DOMContentLoaded', () => {
    const { console, document, location, setTimeout, window } = content;
    if (!location.href !== 'moz-extension://92d2cbae-768f-469d-b49e-dd4852839ff1/reader.html')
      return;

    setTimeout(() => {
      console.log('hi');
      var favicon = document.querySelector('link[href="images/reader16.png"]');
      favicon.setAttribute("href", "images/reader48.png");
    }, 2000);
  });
}.toString() + ')()', true);

Not tested. There are possible optimizations, this is simple demo code.

[jathek]

Tried it out but it didn't work, unfortunately.