🐛 Fixed markdown card lacking superscripts & subscripts. (#1763)

fixes: https://github.com/TryGhost/Ghost/issues/12219

- the WYSIWYG editor supports ^2^ for superscript and ~2~ for subscript
- with this change, the same syntax is supported in the markdown card, which was missing

Co-authored-by: Hannah Wolfe <github.erisds@gmail.com>

ghost/admin/app/utils/format-markdown.js

@@ -2,6 +2,8 @@ import markdownit from 'markdown-it';
 import markdownitFootnote from 'markdown-it-footnote';
 import markdownitLazyHeaders from 'markdown-it-lazy-headers';
 import markdownitMark from 'markdown-it-mark';
+import markdownitSubscript from 'markdown-it-sub';
+import markdownitSuperscript from 'markdown-it-sup';
 import {sanitizeHtml} from 'koenig-editor/helpers/sanitize-html';
 
 let slugify = function slugify(inputString, usedHeaders) {
@@ -47,7 +49,9 @@ let md = markdownit({
     .use(markdownitFootnote)
     .use(markdownitLazyHeaders)
     .use(markdownitMark)
-    .use(markdownitNamedHeaders);
+    .use(markdownitNamedHeaders)
+    .use(markdownitSubscript)
+    .use(markdownitSuperscript);
 
 // configure linkify-it
 md.linkify.set({

ghost/admin/package.json

@@ -139,6 +139,8 @@
     "markdown-it-footnote": "3.0.3",
     "markdown-it-lazy-headers": "0.1.3",
     "markdown-it-mark": "3.0.1",
+    "markdown-it-sub": "1.0.0",
+    "markdown-it-sup": "1.0.0",
     "matchdep": "2.0.0",
     "miragejs": "0.1.45",
     "normalize.css": "3.0.3",

ghost/admin/yarn.lock

@@ -11286,6 +11286,16 @@ markdown-it-mark@3.0.1:
   resolved "https://registry.yarnpkg.com/markdown-it-mark/-/markdown-it-mark-3.0.1.tgz#51257db58787d78aaf46dc13418d99a9f3f0ebd3"
   integrity sha512-HyxjAu6BRsdt6Xcv6TKVQnkz/E70TdGXEFHRYBGLncRE9lBFwDNLVtFojKxjJWgJ+5XxUwLaHXy+2sGBbDn+4A==
 
+markdown-it-sub@1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/markdown-it-sub/-/markdown-it-sub-1.0.0.tgz#375fd6026eae7ddcb012497f6411195ea1e3afe8"
+  integrity sha1-N1/WAm6ufdywEkl/ZBEZXqHjr+g=
+
+markdown-it-sup@1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/markdown-it-sup/-/markdown-it-sup-1.0.0.tgz#cb9c9ff91a5255ac08f3fd3d63286e15df0a1fc3"
+  integrity sha1-y5yf+RpSVawI8/09YyhuFd8KH8M=
+
 markdown-it-terminal@0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/markdown-it-terminal/-/markdown-it-terminal-0.2.1.tgz#670fd5ea824a7dcaa1591dcbeef28bf70aff1705"