Enable MathJax on any web page

mathjax.js

// Add the following bookmarklet:
// javascript:(async function () {var x = await fetch('https://gist.githubusercontent.com/nkgsv/db4a65eb27a40f812f22782cab823755/raw/bc09ef1d4bbabf3dbe9c5db1496161654a88f286/mathjax.js'); x = await x.text(); eval(x);})();
// or simply copy and paste the following code to Developer Console:

var script = document.createElement('script');
script.type = 'text/javascript';
script.src = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/MathJax.js?config=TeX-AMS_HTML';
document.head.appendChild(script);

var render = function() {
  if (window.MathJax === undefined) {
    window.setTimeout(render, 100);
  } else {
    MathJax.Hub.Config({
        extensions: ["tex2jax.js"],
        jax: ["input/TeX", "output/HTML-CSS"],
        tex2jax: {
        inlineMath: [ ["\(","\)"], ['$','$'] ],
        displayMath: [ ['$$','$$'], ["\\[","\\]"] ],
        processEscapes: true
      },
      "HTML-CSS": { fonts: ["TeX"] }
    });
    MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
  }
}

render();