layouts/shortcodes/asciinema.html

<div id='{{ index .Params "src" }}_asc_cast'></div>
<script src="{{ .Site.BaseURL }}js/asciinema-player.min.js"></script>
<link rel="stylesheet" type="text/css" href="{{ .Site.BaseURL }}css/asciinema-player.css" />
<script>
AsciinemaPlayer.create('/casts/{{ index .Params "src" }}.cast', document.getElementById('{{ index .Params "src" }}_asc_cast'),
{ {{ range $key, $value := .Params }}
    {{- if ne $key "src" }}
        {{- $key }}: {{ $value }},
    {{- end }}
{{- end }}});
</script>