feat(MathJax): Add support for MathJax extension, e.g. physics package

_includes/js-selector.html

@@ -70,30 +70,6 @@
 {% capture script %}{{ js_dist }}{{ js }}.min.js{% endcapture %}
 <script defer src="{{ script | relative_url }}"></script>
 
-{% if page.math %}
-  <!-- MathJax -->
-  <script>
-    /* see: <https://docs.mathjax.org/en/latest/options/input/tex.html#tex-options> */
-    MathJax = {
-      tex: {
-        /* start/end delimiter pairs for in-line math */
-        inlineMath: [
-          ['$', '$'],
-          ['\\(', '\\)']
-        ],
-        /* start/end delimiter pairs for display math */
-        displayMath: [
-          ['$$', '$$'],
-          ['\\[', '\\]']
-        ],
-        /* equation numbering */
-        tags: 'ams'
-      }
-    };
-  </script>
-  <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js?features=es6"></script>
-  <script id="MathJax-script" async src="{{ site.data.origin[type].mathjax.js | relative_url }}"></script>
-{% endif %}
 
 <!-- Pageviews -->
 {% if page.layout == 'post' %}

_includes/mathjax-support.html

@@ -0,0 +1,22 @@
+<script>
+/* see: <https://docs.mathjax.org/en/latest/options/input/tex.html#tex-options> */
+/* MathJax extensions can be found: <https://docs.mathjax.org/en/latest/input/tex/extensions/index.html> */
+MathJax = {
+    tex: {
+    /* start/end delimiter pairs for in-line math */
+    inlineMath: [
+        ['$', '$'],
+        ['\\(', '\\)']
+    ],
+    /* start/end delimiter pairs for display math */
+    displayMath: [
+        ['$$', '$$'],
+        ['\\[', '\\]']
+    ],
+    /* equation numbering */
+    tags: 'ams'
+    }
+};
+</script>
+<script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js?features=es6"></script>
+<script id="MathJax-script" async src="{{ site.data.origin[type].mathjax.js | relative_url }}"></script>

_layouts/default.html

@@ -78,6 +78,11 @@
 
     {% include js-selector.html lang=lang %}
 
+    <!-- MathJax -->
+    {% if page.math %}
+      {% include mathjax-support.html %}
+    {% endif %}
+
     {% if page.mermaid %}
       {% include mermaid.html %}
     {% endif %}