Tampermonkey User Script to add MathJax to, e.g., Trello

add_mathjax.js

// ==UserScript==
// @name         MathJax
// @namespace    http://tampermonkey.net/
// @version      2.0
// @description  Add Mathjax to webpages
// @author       Nathan Hunt
// @match        https://trello.com/*
// @grant        none
// ==/UserScript==

// Note that github blocks this <.< I haven't found a viable workaround.

// See http://docs.mathjax.org/en/latest/web/configuration.html for
// instructions on loading mathjax and
// http://docs.mathjax.org/en/latest/advanced/typeset.html for
// instructions on using mathjax with dynamic webpages

(function() {
    'use strict'

    if (window.MathJax !== undefined) {
        return
    }

    window.MathJax = {
        tex: {
            inlineMath: [['$', '$'], ['\\(', '\\)']]
        },
        svg: {
            fontCache: 'global'
        }
    };

    let script = document.createElement('script');
    script.src = 'https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-svg.js';
    script.async = true;
    document.head.appendChild(script);

    // Run mathjax every second
    (function typesetForever() {
        window.setTimeout(typesetForever, 1000)
        if (window.MathJax.typeset !== undefined) { // done loading
            window.MathJax.typeset()
        }
    })()
})()

Someone I shared this with pointed out that this causes an infinite recursion, and something like the following would be more robust:

    function typesetNow() {
        if (window.MathJax.typeset !== undefined) { // done loading
            window.MathJax.typeset();
        }
    }
    window.setInterval(typesetNow, 1000);