static/shared/outline/tree.tmpl

<!--
  Copyright 2021 The Go Authors. All rights reserved.
  Use of this source code is governed by a BSD-style
  license that can be found in the LICENSE file.
-->

{{define "treeitems"}}
  {{range .}}
    <li>
      <a href="#{{.ID}}">{{.Text}}</a>
      {{if and .Children (lt .Level 4)}}
        <ul>
          {{template "treeitems" .Children}}
        </ul>
      {{end}}
    </li>
  {{end}}
{{end}}

{{define "tree-nav"}}
  <ul class="go-Tree js-tree" role="tree">
    {{template "treeitems" .}}
  </ul>
{{end}}