Why is there no support for MathJax in chat?

Question

The question Should chat have TeX support was first asked 3½ years ago, and it has been asked at intervals since then. I am not asking that question. I know that chat should have TeX support and so does everyone else. My questions are, why hasn't this been done and when will it be done? The lack of MathJax support in chat is a serious problem with the site, and it should be fixed as soon as possible, preferably today.

I am aware of the existing solutions such as greasemonkey scripts. I use them myself. They do not solve the problem because while they allow one to receive formatted mathematics, they don't allow one to send it, unless the recipient also has a script installed. But in general I can't expect the person I am talking to will have one installed. Then I think I am sending “No, you need to consider $\int_0^\infty \def\O{\mathcal O} \O\left(\operatorname{erf}(\frac x2)\right)\;dx$” but the hapless loser I am trying to help only sees “No, you need to consider \int_0^\infty \def\O{\mathcal O} \O\left(\operatorname{erf}(\frac x2)\right)\;dx”.

When a discussion goes on in comments, SE posts a notice telling the people involved to take the discussion to chat:

That sounds great at first, but it is completely unhelpful, because if the discussion is taken to chat, you will no longer be able to actually discuss mathematics. And the prior discussion, imported automatically, will look like this to the person you are trying to help:

It seems to me completely obvious that this feature is crucial, and its lack should have been addressed years ago, and yet it has not been. So I repeat: What is causing the delay on this? When will this be fixed? And if it's been decided for some reason that it will never happen, then what is going to be done instead? What's the point of having chat at all, when it doesn't work? The purpose of the site is to ask and answer questions about mathematics, and the only purpose of chat is to support that. Other features of the site assume that it will. But in its present form, it does not and it cannot.

Answer 1

I don't really relish being the bearer of bad news, but here's a recent answer by Shog9 on Meta Stack Exchange:

This request was discussed by the team on April 9th, 2014. The potential rendering cost would be such that it would need to be a per-room and per-user option; this would then create a situation where users would potentially never be sure how their messages would look to other readers - in other words, little better than the user-script solution currently available.

Answer 2

I can offer the following piece of information about trying to tweak chatjax to work on the chat page.

Usually sites enable Mathjax by using javascript in their global header, so having specific options for certain pages doesn't work well with this configuration.

That is, trying to have chatjax work as specific option on the chat page would probably conflict with the global header.

My hypothesis on the delay would be trying to figure out how to have page specific options in Mathjax not conflict with the global configuration. I don't know the inner workings of the site but that is my guess.

Answer 3

If you are using firefox like me, then using this script on Greasemonkey add-on may fix the issue perfectly. To install this script just click on "New user script" in the add-on then copy and paste this as it is.

// ==UserScript==
// @name     Unnamed Script 781864
// @version  1
// @grant    none
// ==/UserScript==

var stop = false;
var update = true;

if(window.MathJax === undefined)
{
    var script = document.createElement("script");
    script.type="text/javascript";
    script.src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML";
    var config='MathJax.Hub.Config({"HTML-CSS": { ' +
               'webFont: "TeX", ' +
               'preferredFont: "TeX", ' + 
               'availableFonts: ["STIX","TeX"], ' +
               'linebreaks: { automatic:true }, '+
               'EqnChunk: (MathJax.Hub.Browser.isMobile ? 10 : 50) }, ' +
               'tex2jax: { inlineMath: [ ["$", "$"] ], displayMath: [ ["$$","$$"] ], processEscapes: true, ignoreClass: "tex2jax_ignore|dno|last-message" }, ' +
               'TeX: { extensions: ["mhchem.js", "enclose.js", "cancel.js"], noUndefined: { attributes: { mathcolor: "red", mathbackground: "#FFEEEE", mathsize: "90%25" } } }, ' +
               'messageStyle: "none"}); ' +
               'MathJax.Hub.Startup.onload();';

    if(window.opera) {
        script.innerHTML = config;
    } else {
        script.text = config;
    }

    document.getElementsByTagName("head")[0].appendChild(script);

    $('#chat-buttons').prepend('<button class="button" id="math-button">MathJax</button>');
	$('#math-button').click(function() {
        $('body').append('<div id="jax-popup-bg" class="wmd-prompt-background" style="position: fixed; top: 0px; z-index: 1000; opacity: 0.5; left: 0px; width: 100%; height: 100%;"></div>' +
                         '<div id="jax-popup" style="top: 50%; left: 50%; display: block; padding: 10px; position: fixed; width: 150px; z-index: 1001; margin-top: -93.5px; margin-left: -113px;" class="wmd-prompt-dialog">' +
                             '<div align="center">' +
                                 '<b>MathJax</b><br>' + 
                                 'Interval:' +
                                 '<input type="text" id="jax-heartbeat" style="width: 80px; margin-left: 10px" title="In miliseconds" value="' + beatInterval + '"/><br>' +
                                 '<input type="checkbox" id="jax-update" title="Use an ajax handler instead of a heartbeat">Update</input>' +
                                 '<input type="checkbox" id="jax-disable" style="margin-left: 10px" title="Temporarily stops MathJax from updating">Disable</input>' +
                             '</div>' +

                             '<button id="jax-ok" class="button">Ok</button>' +
                             '<button id="jax-cancel" style="margin-left: 10px" class="button">Cancel</button>' +
                             '<script type="text/javascript">' +
                                 '$("#jax-update").prop("checked", update);' +
								 '$("#jax-disable").prop("checked", stop);' +
                                 '$("#jax-heartbeat").prop("disabled", !update || stop);' +
								 '$("#jax-update").prop("disabled", stop);' +

                                 '$("#jax-ok").click(function() {' +
									 'if($.isNumeric($("#jax-heartbeat").val()) && parseInt($("#jax-heartbeat").val()) >= 1000) {' +
										 'if($("#jax-update").prop("checked") && !$("#jax-disable").prop("checked")) {' +
											 'beatInterval = parseInt($("#jax-heartbeat").val());' +
                                         '}' +

                                         'if(!$("#jax-disable").prop("checked")) {' +
											 'update = $("#jax-update").prop("checked");' +
                                         '}' +

                                         'stop = $("#jax-disable").prop("checked");' +
										 '$("#jax-popup").remove();' +
                                         '$("#jax-popup-bg").remove();' +
                                     '} else {' +
                                         'alert("Values must be numeric and no less than 1000");' +
                                     '}' +
                                 '});' +

                                 '$("#jax-cancel").click(function() {' +
									 '$("#jax-popup").remove();' +
									 '$("#jax-popup-bg").remove();' +
                                 '});' +

                                 '$("#jax-update").click(function() {' +
									 '$("#jax-heartbeat").prop("disabled", !$("#jax-update").prop("checked"));' +
                                 '});' +

                                 '$("#jax-disable").click(function() {' +
									 '$("#jax-heartbeat").prop("disabled", $("#jax-disable").prop("checked"));' +
									 '$("#jax-update").prop("disabled", $("#jax-disable").prop("checked"));' +
                                 '});' +
                             '</script>' +
                         '</div>');
    });
} else {
    if(window.MathJax !== undefined)
        MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
}

$('document').ready(function() {
    beat();
});

$('html').ajaxComplete(function() {
    if(!update && !stop)
        MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
});

var beatInterval = 5000;
function beat() {
    setTimeout(function() { 
        if(window.MathJax !== undefined)
        {
            MathJax.Hub.Queue(["Typeset", MathJax.Hub]);

            $.each($('script[type="math/tex"]'), function(index, value) { 
                if ($(value).parent().data('events') === undefined) { 
					$(value).parent().click(function() { 
						if ($(value).parent().html().split($(value).html() || []).length - 1 === 1) {
							$(value).parent().append(' \\$' + $(value).html() + '\\$');
                        }
                    }); 
                } 
            });
        }

        if(update && !stop)
            beat();

    }, beatInterval);
};
```