hexo ejs hierarchical categories display

example.ejs

<%
function displayCategories(parent = undefined) { // start with no parent
  site.categories
    .find({ parent }) // warehouse allows for complex queries
    .sort("name") // sorting .sort("fieldName", 1) ascending or .sort("fieldName", -1) descending
    .each(function(category) {
      // count the child categories
      const childCount = site.categories.find({ parent: category._id }).count();
      %>
      <li>
        <a href="<%=url_for(category.path)%>"><%=category.name%></a>
        
        <% if (childCount > 0) { // recurse if there are child categories %>
          <ul>
            <% displayCategories(category._id); %>
          </ul>
        <% } %>
      </li>
      <%
    });
}
%>


<h3>Hierarchical category display</h3>

<ul>
  <% displayCategories(); %>
</ul>