hugo-geekblog/layouts/shortcodes/mermaid.html

{{ if not (.Page.Scratch.Get "mermaid") }}
<!-- Include mermaid only first time -->
<script defer src="{{ index .Site.Data.assets "js/mermaid.min.js" | relURL }}"></script>
<script>
    document.addEventListener("DOMContentLoaded", function(event) {
        mermaid.initialize({
            flowchart: { useMaxWidth: true }
        });
    });
</script>
{{ .Page.Scratch.Set "mermaid" true }}
{{ end }}

<pre class="gblog-mermaid mermaid{{ with .Get "class" }} {{ . }}{{ end }}">
  {{- .Inner -}}
</pre>