scinote-web/app/views/project_comments/_list.html.erb

<%
  day = 366
  current_day = DateTime.current.strftime('%j').to_i
%>
<% comments.each do |comment| %>
  <%
    comment_day = comment.created_at.strftime('%j').to_i

    if comment_day < current_day and comment_day < day then
    day = comment.created_at.strftime('%j').to_i
  %>
  <li class="comment-date-separator">
    <p class="text-center"><%= comment.created_at.strftime('%d.%m.%Y') %></p>
  </li>
  <% end %>
  <li class="comment">
    <%= render 'project_comments/comment.html.erb', comment: comment %>
  </li>
<% end %>