UserScript: macOS Catalina Chrome v78-79 Hiragino Font Fix

script.js

// ==UserScript==
// @name         macOS Catalina Chrome v78-79 Hiragino Font Fix
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  This will no longer be needed after chrome v80.
// @author       fukayatsu
// @match        http://*/*
// @match        https://*/*
// @grant        GM_addStyle
// @run-at       document-idle
// ==/UserScript==

(function() {
    'use strict';

    const selectors = [
        '.r-gwet1z', // twitter
        'body' // default
    ];

    const replaceFontPairs = {
        "ヒラギノ角ゴ Pro W3":      "HiraKakuPro-W3",
        "Hiragino Maru Gothic Pro": "HiraMaruPro-W4"
    }

    const replaceFont = (selector) => {
        const elem = document.querySelector(selector);
        if (!elem) { return }

        const originalFontFamily = window.getComputedStyle(elem)['font-family'];

        let ff = originalFontFamily;

        for (const key in replaceFontPairs) {
            const fixedFont = replaceFontPairs[key];
            if (ff.includes(fixedFont)) { continue; }

            ff = ff.replace(key, replaceFontPairs[key]);
        }

        if (ff == originalFontFamily) { return }

        const styleToAdd = `${selector} { font-family: ${ff} !important; }`;
        GM_addStyle(styleToAdd);
        console.log("New style added:", styleToAdd);
    };

    setTimeout(() => {
        for (const selector of selectors) {
            replaceFont(selector);
        }
    }, 1000);
})();