CF DarkReader Tex Formulae Inversion

cf-tex-inversion.js

// ==UserScript==
// @name         CF DarkReader invert Tex Formulae
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://codeforces.com/*
// @icon         https://www.google.com/s2/favicons?domain=codeforces.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    window.addEventListener('load', () => {
        // Update callback
        const update = () => {
            let invert = 100;
            if (document.documentElement.getAttribute('data-darkreader-scheme') !== 'dark') invert = 0;
            document.querySelectorAll('img.tex-formula').forEach((el) => el.style.filter = `invert(${invert}%)`);
        };

        // Initial update
        update();

        // Mutation observer
        const htmlTag = document.documentElement;
        const observer = new MutationObserver(update);
        observer.observe(htmlTag, {attributes: true, attributeFilter: ['data-darkreader-scheme']});
    });
})();