TeX formatting in other comments in the same post is lost when the comment list is updated

Question

If there's any TeX formatting in comments of a post, after you add a comment to that post, or click "add / show n more comments", all formulae are reverted to $...$.

Steps to reproduce:

1. Go to a post where there are formulae in the comments, e.g. Dot product in coordinates
2. Click the "add / show 1 more comment" link, or add a comment.
3. See that formula ($v \cdot w = |v| |w| \cos \theta$) is reverted to code i.e. ＄v \cdot w = |v| |w| \cos \theta＄.

Answer 1

status-completed. See Re-render MathJax in comments.

---

A workaround is to use the following userscript. _{^{(can some GM gurus see if it's possible to remove all those unsafeWindows?)}}

// ==UserScript==
// @name           Fix TeX related problems on math.SE
// @namespace      http://networkpx.googlecode.com
// @description    Fix TeX related problems on math.SE
// @include        https://math.meta.stackexchange.com/*
// @include        http://math.stackexchange.com/*
// ==/UserScript==

var rl = unsafeWindow.removeLoader;
unsafeWindow.removeLoader = function(){
    rl();
    unsafeWindow.styleCode();
}

---

There are 2 options to fix this problem.

Option 1:

1. Edit "question.js".
2. Find the "var n = function (r, q)" function, inside the comments object.

3. Modify this function to:

   var p = h(r, " > table > tbody");
   if (p.children().length > 0) {
       p.children().remove()
   }
   p.append(q);
   d();
   o();
   if (typeof MathJax != "undefined")                // <--
       MathJax.Hub.Queue(["Typeset", MathJax.Hub]);  // <--
   removeLoader()
   

This should fully solve the problem (I haven't tested), but it requires changing a file that is shared by every site.

Option 2:

1. Edit any Javascript file, e.g. "math-tex.js", after "master.js" is loaded.

2. Add these lines of code:

   var rl = removeLoader;
   removeLoader = function(){
     rl();
     MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
   }
   

This relies on the loader is being removed when a comment is successfully added, fetched or edited. It is pretty hackish.

Answer 2

Here is a way to eliminate the need for unsafeWindow in KennyTM’s awesome workaround. I also added cstheory.stackexchange.com and the corresponding Meta.

// ==UserScript==
// @name           Fix TeX related problems on Stack Exchange sites
// @namespace      https://math.meta.stackexchange.com/questions/1114
// @description    Fix TeX related problems on Stack Exchange sites
// @include        https://math.stackexchange.com/*
// @include        https://math.meta.stackexchange.com/*
// @include        https://cstheory.stackexchange.com/*
// @include        http://meta.cstheory.stackexchange.com/*
// ==/UserScript==

var HTML_NS = 'http://www.w3.org/1999/xhtml';
var script = document.createElementNS(HTML_NS, 'script');
script.type = 'text/javascript';
script.appendChild(document.createTextNode(' \
    void function(){ \
        var rl = removeLoader; \
        removeLoader = function(){ \
            rl(); \
            styleCode(); \
        } \
    }(); \
'));
document.body.appendChild(script);

(Edit: I changed the value of @namespace because now I realized that if I use other people’s URL as @namespace, it defeats the purpose of namespaces.)

Tested on Firefox 3.6.12 with Greasemonkey 0.8.20100408.6. I used the following posts to test the functionality.

• Dot product in coordinates
• https://cstheory.stackexchange.com/questions/34/how-hard-is-unshuffling-a-string/1082#1082

In principle, the same user script should work on other Stack Exchange websites using MathJax if you add the corresponding @include lines.

Answer 3

(reposting analysis of the bug from related but not exact duplicate question that was closed.)

Example here: Question Relating Gamma Function to Riemann Zeta function evaluated at integers (see comments under Robin Chapman's answer).

When the page is loaded, TeX is processed for an initial set of visible comments. When clicking on "show more comments" below the answer, the Tex processor is not invoked unless the additional comments contain TeX. Comments in the original visible set that contain TeX and that are shuffled when the full set of comments appear, will revert to non-graphical plain text (dollar signs, TeX code).

I experimented on this in the example by posting another comment with TeX code. In the presence of "more comments" that do contain TeX, the display of TeX in all comments was re-processed after the click and worked correctly. So there is apparently no run of the TeX processing (for the entire displayed page) when additional comments are displayed, unless TeX code is detected in those comments. But the TeX display can be disturbed if lower-ranked comments chronologically precede top-ranked comments containing TeX.