Display Mathjax expression (including LaTeX and MathML) in the trivial web page

douban.math.js

// ==UserScript==
// @name mathjax for douban
// @namespace jiangzuoyan@gmail.com
// @author Changsheng Jiang<jiangzuoyan@gmail.com> // 感谢原作者，并且我把math_jax_src改回原来的mathjax.org了
// @include http://*.douban.com/*
// @description texify formula using mathjax
// @date 2011-07-12
// @version 20110712
// ==/UserScript==

(function() {
   function check_init_mathjax() {
     if (typeof MathJax == "undefined") {
       // var math_jax_src = "http://img3.douban.com/static/book/math/MathJax.js?config=TeX-AMS-MML_HTMLorMML&delayStartupUntil=configured";
       var math_jax_src = "http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML&delayStartupUntil=configured";
       var script = document.createElement("script");
       script.src = math_jax_src;
       script.type = "text/javascript";
       script.addEventListener(
         "load",
         function() {
           MathJax.Hub.Config(
             {
               jax: ["input/TeX", "output/HTML-CSS"],
               extensions: ["tex2jax.js","TeX/AMSmath.js","TeX/AMSsymbols.js", "TeX/noUndefined.js"],
               tex2jax: {
                 inlineMath: [ ['$','$'], ["\\(","\\)"], ["[;", ";]"] ],
                 displayMath: [ ['$$','$$'], ["\\[","\\]"] ],
                 skipTags: ["script","noscript","style","textarea", "pre"],
                 ignoreClass: "tex2jax_ignore",
                 processEscapes: true,
                 processEnvironments: true,
                 preview: "TeX"
               },
               showProcessingMessages: true
             });
           MathJax.Hub.Configured();
         }, false);
       document.body.appendChild(script);
     }
   }
   var script = document.createElement("script");
   script.textContent = "(" + check_init_mathjax.toString() + ")();";
   document.body.appendChild(script);
 })();

There is an easier way you could do all of this.

Simply interpret all alternate text for images as latex, which is how most websites with maths images do it.

You just have to make sure that if the alt text is not latex then the userscript understands that so it doesn't break the page.

Sadly, my scripting skills are not that good.