Merge pull request #81 from theme-next/fix-math-load

Fix #78

Author: wafer-li

layout/_third-party/math/index.swig

@@ -1,10 +1,20 @@
 {% if theme.math.enable %}
-  {% if not theme.math.per_page or (page.total or page.mathjax) %}
+  {% set is_index_has_math = false %}
+
+  {# At home, check if there has `mathjax: true` post #}
+  {% if is_home() %}
+    {% for post in page.posts %}
+      {% if post.mathjax and not is_index_has_math %}
+        {% set is_index_has_math = true %}
+      {% endif %}
+    {% endfor %}
+  {% endif %}
+
+  {% if not theme.math.per_page or (is_index_has_math or page.mathjax) %}
     {% if theme.math.engine == 'mathjax' %}
       {% include 'mathjax.swig' %}
     {% elif theme.math.engine == 'katex' %}
       {% include 'katex.swig' %}
    {% endif %}
   {% endif %}
 {% endif %}
-