Update Org to MathJax 3

["Rudolf Adamkovič" <salutis@me.com>]

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Hello smart people!

With all the talk about Emacs 29, I figured we should update Org Mode to
use MathJax 3, to catch up with the rest of the world.

From the documentation (for MathJax 3.0 released in 2019):

> Version 3.0 of MathJax is a complete rewrite of MathJax from the
> ground up, and its usage and configuration is significantly different
> from that of MathJax version 2.

In practice, MathJax 3.2 renders mathematics faster and better, plus it
significantly improves LaTeX support.  For instance, one can typeset
calculus with the built-in (!) 'physics' package, like in LaTeX.

More information on the recent progress (made in 2019-2021):

https://docs.mathjax.org/en/latest/upgrading/whats-new-3.0.html
https://docs.mathjax.org/en/latest/upgrading/whats-new-3.1.html
https://docs.mathjax.org/en/latest/upgrading/whats-new-3.2.html

See the attached [working, but WIP] patch.

My question for you:

How do we change the 'org-html-mathjax-options'?

- 'scale' has now the value in [0, 1] and not in [0, 100]
- 'scale' should exist as a number and not string
- 'font' did not make it to MathJax 3 [*]
- 'linebreaks' did not make it to MathJax 3 [*]
- 'autonumber' has the values in lowercase now
- 'autonumber' became 'tags' in MathJax terminology

[*] coming in MathJax 4, currently in alpha

How does Org mode approach these kind of breaking changes?

Rudy


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From ca2eaf5bcc9ea01e764f6088e37d74ec2be6e426 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rudolf=20Adamkovi=C4=8D?= <salutis@me.com>
Date: Fri, 7 Oct 2022 15:03:48 +0200
Subject: [PATCH] ox-html: Use MathJax 3 instead of 2.7

* lisp/ox-html.el (org-html-mathjax-options): WIP
* lisp/ox-html.el (org-html-mathjax-template): WIP
---
 lisp/ox-html.el | 51 +++++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/lisp/ox-html.el b/lisp/ox-html.el
index 9b77e4f8d..c6242d4bc 100644
--- a/lisp/ox-html.el
+++ b/lisp/ox-html.el
@@ -1166,12 +1166,12 @@ See `format-time-string' for more information on its components."
 ;;;; Template :: Mathjax
 
 (defcustom org-html-mathjax-options
-  '((path "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_HTML" )
-    (scale "100")
+  '((path "https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js")
+    (scale "1") ;; TODO: 0-1 AND NOT 0-100; NUMBER AND NOT STRING
     (align "center")
-    (font "TeX")
-    (linebreaks "false")
-    (autonumber "AMS")
+    (font "TeX") ;; TODO: NOT SUPPORTED
+    (linebreaks "false") ;; TODO: NOT SUPPORTED
+    (autonumber "ams") ;; TODO: NOW CALLED TAGS AND IN LOWERCASE
     (indent "0em")
     (multlinewidth "85%")
     (tagindent ".8em")
@@ -1244,27 +1244,28 @@ For further information about MathJax options, see the MathJax documentation:
 			     (const "right")))))
 
 (defcustom org-html-mathjax-template
-  "<script type=\"text/x-mathjax-config\">
-    MathJax.Hub.Config({
-        displayAlign: \"%ALIGN\",
-        displayIndent: \"%INDENT\",
-
-        \"HTML-CSS\": { scale: %SCALE,
-                        linebreaks: { automatic: \"%LINEBREAKS\" },
-                        webFont: \"%FONT\"
-                       },
-        SVG: {scale: %SCALE,
-              linebreaks: { automatic: \"%LINEBREAKS\" },
-              font: \"%FONT\"},
-        NativeMML: {scale: %SCALE},
-        TeX: { equationNumbers: {autoNumber: \"%AUTONUMBER\"},
-               MultLineWidth: \"%MULTLINEWIDTH\",
-               TagSide: \"%TAGSIDE\",
-               TagIndent: \"%TAGINDENT\"
-             }
-});
+  "<script>
+  window.MathJax = {
+    tex: {
+      ams: {
+        multlineWidth: '%MULTLINEWIDTH'
+      },
+      tags: '%AUTONUMBER',
+      tagSide: '%TAGSIDE',
+      tagIndent: '%TAGINDENT'
+    },
+    chtml: {
+      scale: %SCALE,
+      displayAlign: '%ALIGN',
+      displayIndent: '%INDENT'
+    },
+    svg: {
+      scale: %SCALE
+    }
+  };
 </script>
-<script src=\"%PATH\"></script>"
+
+<script id=\"MathJax-script\" async src=\"%PATH\"></script>"
   "The MathJax template.  See also `org-html-mathjax-options'."
   :group 'org-export-html
   :type 'string)
-- 
2.37.3


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-- 
"Mathematics takes us still further from what is human into the region
of absolute necessity, to which not only the actual world, but every
possible world, must conform."
-- Bertrand Russell, 1902

Rudolf Adamkovič <salutis@me.com> [he/him]
Studenohorská 25
84103 Bratislava
Slovakia