jekyll-theme-chirpy/_includes/comments/giscus.html

<!-- https://giscus.app/ -->
<script>
  (function () {
    const themeMap = Theme.newThemeMap('light', 'dark_dimmed');
    const initTheme = themeMap[Theme.resolvedTheme];

    let lang = '{{ site.comments.giscus.lang | default: lang }}';
    {%- comment -%} https://github.com/giscus/giscus/tree/main/locales {%- endcomment -%}
    if (lang.length > 2 && !lang.startsWith('zh')) {
      lang = lang.slice(0, 2);
    }

    let giscusAttributes = {
      src: 'https://giscus.app/client.js',
      'data-repo': '{{ site.comments.giscus.repo}}',
      'data-repo-id': '{{ site.comments.giscus.repo_id }}',
      'data-category': '{{ site.comments.giscus.category }}',
      'data-category-id': '{{ site.comments.giscus.category_id }}',
      'data-mapping': '{{ site.comments.giscus.mapping | default: 'pathname' }}',
      'data-strict' : '{{ site.comments.giscus.strict | default: '0' }}',
      'data-reactions-enabled': '{{ site.comments.giscus.reactions_enabled | default: '1' }}',
      'data-emit-metadata': '0',
      'data-theme': initTheme,
      'data-input-position': '{{ site.comments.giscus.input_position | default: 'bottom' }}',
      'data-lang': lang,
      'data-loading': 'lazy',
      crossorigin: 'anonymous',
      async: ''
    };

    let giscusNode = document.createElement('script');
    Object.entries(giscusAttributes).forEach(([key, value]) =>
      giscusNode.setAttribute(key, value)
    );

    const $footer = document.querySelector('footer');
    $footer.insertAdjacentElement("beforebegin", giscusNode);

    addEventListener('message', (event) => {
      if (event.source === window && event.data && event.data.id === Theme.eventId) {
        const newTheme = themeMap[Theme.resolvedTheme];

        const message = {
          setConfig: {
            theme: newTheme
          }
        };

        const iframe = document.querySelector('.giscus-frame');

        if (!iframe) {
          return;
        }

        if (iframe.classList.contains('giscus-frame--loading')) {
          let url = new URL(iframe.src);
          url.searchParams.set('theme', newTheme);
          iframe.src = url.toString();
        }

        iframe.contentWindow.postMessage({ giscus: message }, 'https://giscus.app');
      }
    });
  })();
</script>