User script to disable MathJax display math in comments on Stack Exchange sites

disable_display_math_in_comments.user.js

// ==UserScript==
// @name        Disable display math in comments
// @namespace   https://github.com/vyznev/
// @description Forces all MathJax elements in comments to be rendered inline
// @author      Ilmari Karonen
// @version     1.1
// @match       *://*.stackexchange.com/*
// @match       *://*.mathoverflow.net/*
// @homepageURL	http://meta.math.stackexchange.com/questions/23250/disable-display-math-in-comments
// @grant       none
// @run-at      document-start
// ==/UserScript==

var inject = function () {
	MathJax.Hub.Register.MessageHook( "Begin Process", function (message) {
		var elements = message[1];
		var selector = '.comment script[type="math/tex; mode=display"]';
		$(elements).find(selector).attr('type', 'math/tex');
	} );
};
var script = document.createElement('script');
script.type = 'text/x-mathjax-config';
script.textContent = "(" + inject + ")();";

var parent = (document.head || document.documentElement);
if (parent) parent.appendChild(script);
else {
  // work-around for https://github.com/greasemonkey/greasemonkey/issues/2996
  var obs = new MutationObserver(function () {
    var parent = (document.head || document.documentElement);
    if (parent) { obs.disconnect(); parent.appendChild(script); }
  });
  obs.observe(document, {childList: true});
}