blog/.themes/classic/source/_includes/disqus.html

{% comment %} Load script if disquss comments are enabled and `page.comments` is either empty (index) or set to true {% endcomment %}
{% if site.disqus_short_name and page.comments != false %}
<script type="text/javascript">
      var disqus_shortname = '{{ site.disqus_short_name }}';
      {% if page.comments == true %}
        {% comment %} `page.comments` can be only be set to true on pages/posts, so we embed the comments here. {% endcomment %}
        // var disqus_developer = 1;
        var disqus_identifier = '{{ canonical }}';
        var disqus_url = '{{ canonical }}';
        var disqus_script = 'embed.js';
      {% else %}
        {% comment %} As `page.comments` is empty, we must be on the index page. {% endcomment %}
        var disqus_script = 'count.js';
      {% endif %}
    (function () {
      var dsq = document.createElement('script'); dsq.type = 'text/javascript'; dsq.async = true;
      dsq.src = 'http://' + disqus_shortname + '.disqus.com/' + disqus_script;
      (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(dsq);
    }());
</script>
{% endif %}