Namespace functions and methods

content/en/methods/page/HasShortcode.md

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+---
+title: HasShortcode
+description: Reports whether the given shortcode is called by the given page.
+categories: []
+keywords: []
+action:
+  related: []
+  returnType: bool
+  signatures: [PAGE.HasShortcode NAME]
+---
+
+By example, let's use [MathJax] to render a LaTeX mathematical expression:
+
+[MathJax]: https://www.mathjax.org/
+
+{{< code file="contents/physics/lesson-1.md" lang=markdown >}}
+Albert Einstein’s theory of special relativity expresses
+the fact that mass and energy are the same physical entity
+and can be changed into each other.
+
+{{</* math */>}}
+$$
+E=mc^2
+$$
+{{</* /math */>}}
+
+In the equation, the increased relativistic mass (m) of a
+body times the speed of light squared (c2) is equal to
+the kinetic energy (E) of that body.
+{{< /code >}}
+
+The shortcode is simple:
+
+{{< code file="layouts/shortcodes/math.html" lang=go-html-template >}}
+{{ trim .Inner "\r\n" }}
+{{< /code >}}
+
+Now we can selectively load the required CSS and JavaScript on pages that call the "math" shortcode:
+
+
+{{< code file="layouts/baseof.html" lang=go-html-template >}}
+<head>
+  ...
+  {{ if .HasShortcode "math" }}
+    <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
+    <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
+  {{ end }}
+  ...
+</head>
+{{< /code >}}