Applying classes and attributes to navigation under certain depth conditions

menu.html.twig

{#
/**
 * @file
 * Theme override to display a menu.
 *
 * Available variables:
 * - menu_name: The machine name of the menu.
 * - items: A nested list of menu items. Each menu item contains:
 *   - attributes: HTML attributes for the menu item.
 *   - below: The menu item child items.
 *   - title: The menu link title.
 *   - url: The menu link url, instance of \Drupal\Core\Url
 *   - localized_options: Menu link localized options.
 *   - is_expanded: TRUE if the link has visible children within the current
 *     menu tree.
 *   - is_collapsed: TRUE if the link has children within the current menu tree
 *     that are not currently visible.
 *   - in_active_trail: TRUE if the link is in the active trail.
 */
#}
{% import _self as menus %}

{#
  We call a macro which calls itself to render the full tree.
  @see http://twig.sensiolabs.org/doc/tags/macro.html
#}
{{ menus.menu_links(items, attributes, 0) }}

{% macro menu_links(items, attributes, menu_level) %}
  {% import _self as menus %}

  {%
    set wrapper_classes = [
      (menu_level == 0) ? 'primary-nav__menu js-menu',
      (menu_level == 1) ? 'primary-nav__submenu',
      (menu_level == 2) ? 'primary-nav__tertmenu',
    ]
  %}

  {% if items %}
    <ul class="{{ wrapper_classes|join(' ') }}">
      {% for item in items %}
        {%
          set classes = [
            (menu_level == 0) ? 'primary-nav__item',
            (menu_level == 1) ? 'primary-nav__subitem',
            (menu_level == 2) ? 'primary-nav__tertitem',
            (menu_level == 0 and item.below) ? 'has-submenu js-has-submenu',
            (menu_level == 0 and item.url.options.attributes['data-highlight']) ? 'has-highlight',
            item.in_active_trail ? 'active-trail',
            item.in_active_trail ? 'is-active',
          ]
        %}

        <li{{ item.attributes.addClass(classes) }}>
          {{ link(item.title, item.url) }}
          {% if item.below %}
            {{ menus.menu_links(item.below, attributes, menu_level + 1) }}
          {% endif %}
        </li>
      {% endfor %}
    </ul>
  {% endif %}
{% endmacro %}