Inject MathJax into the page (protocol agnostic).

inject.js

(function () {
    var cdn, config;

    if (typeof MathJax !== "undefined" && MathJax !== null) {
        return;
    }

    config = document.createElement('script');
    config.setAttribute('type', 'text/x-mathjax-config');
    config.innerHTML = "MathJax.Hub.Config({\n  tex2jax: {inlineMath: [['$','$'], ['\\\\(','\\\\)']]}\n});";

    cdn = document.createElement('script');
    cdn.setAttribute('type', 'text/javascript');
    cdn.setAttribute(
        'src',
        window.location.protocol 
            + '//cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML'
    );

    document.head.appendChild(config);

    return document.head.appendChild(cdn);
})();

Needed this for https://www.behind-the-enemy-lines.com/2008/01/are-you-bayesian-or-frequentist-or.html?m=1

Thanks! :)