How to find the following HTML Element

Question

I have a menu with submenu with a structure like this:

<ul>
  <li>
    <a class="navigation-item">Menu Item 1</a>
    <a class="submenu-toggle"><a/>
    <ul class="submenu">
      <li>
        <a class="navigation-item">Submenu Item 1</a>
      </li>
    </ul>
  </li>
</ul>

I want to add a class to submenu-toggle if Submenu Item 1 is selected. How can I find the submenu-toggle in this case?

closest('li') won' work, this will only find the li after the submenu. closest('li > .submenu-toggle') doesn't work either because the .submenu-toggle has to be an ancestor of the submenu item. If I could select the correct li, I could then use find('.submenu-toggle'). But how do I select the correct li?

Answer 1

Regardless of the already above commented approach of mine ...

A real generic one with no jQuery needed, just the closest and the querySelector methods together with css-selectors ... yourInnerElementReference.closest('li:has(.submenu-toggle)').querySelector('.submenu-toggle'). Have a look at the functional :has() CSS pseudo-class

... there is a big chance that the OP does not need any JavaScript based solution at all in order to style the toggle-element. This of cause does not imply that JS is entirely obsolete in order to achieve all of the required menu-behaviors, but I would give even that one a real good try.

.menu {
  display: inline-block;
  
  li {
    margin: 4px 0;
  }
  > li {
    position: relative;
    margin: 12px 0;

    > .toggle {
      position: absolute;
      top: 0;
      right: 0;
    }
  }
}
.submenu:has(a:active, a:focus, a:target) {
  + .toggle {
    color: green;
  }
}

<ul class="menu">
  <li>
    <a href="#">Menu Item 1</a>

    <ul class="submenu">
      <li>
        <a href="#">Submenu Item 1.1</a>
      </li>
      <li>
        <a href="#">Submenu Item 1.2</a>
      </li>
    </ul>
    <div tabindex="0" class="toggle">toggle</div>
  </li>
  <li>
    <a href="#">Menu Item 2</a>

    <ul class="submenu">
      <li>
        <a href="#">Submenu Item 2.1</a>
      </li>
      <li>
        <a href="#">Submenu Item 2.2</a>
      </li>
    </ul>
    <div tabindex="0" class="toggle">toggle</div>
  </li>
</ul>

And whereas the above example-code shows an HTML/CSS-only approach which achieves what the OP did ask for, the next provided example code can be a solution for what the OP actually might really need in terms of ...

• the behavior which one would expect from a nested menu where the submenu structure can be toggled in between its expanded and collapsed state,

• a semantically correct HTML structure and its related CSS rules

• as well as a minimal JS footprint.

function handleNavigationClick(evt) {
  const toggleElement = evt.target.closest('.expand-toggle');

  if (toggleElement) {
    toggleElement.classList.toggle('indicate-expanded');
  }
}
document
  .querySelector('nav')
  .addEventListener('click', handleNavigationClick);

li {
  margin: 4px 0;
}
menu {
  margin: 0;
  padding: 0;
  list-style: none;
}

menu:not(.submenu) {
  display: inline-block;
  
  > li {
    position: relative;
    margin: 12px 0;
  }
}
.submenu {
  display: none;
}

[type="button"].expand-toggle {

  overflow: hidden;
  position: relative;
  width: 1em;
  border: none;
  background: none;
  text-indent: 1em;
  text-wrap: nowrap;

  &:after {
    z-index: -1;
    position: absolute;
    left: -.77em;
    top: .07em;
    content: ">";
  }
  &.indicate-expanded {
    &:after {
      top: .04em;
      content: "v";
    }

    ~ .submenu {
      display: block;
      margin-left: 2em;
    }
  }
}

<nav>
  <menu>
    <li>
      <button type="button" class="expand-toggle" title="toggle submenu display">
        toggle submenu display
      </button>

      <a href="#">Menu Item 1</a>

      <menu class="submenu">
        <li>
          <a href="#">Submenu Item 1.1</a>
        </li>
        <li>
          <a href="#">Submenu Item 1.2</a>
        </li>
      </menu>
    </li>
    <li>
      <button type="button" class="expand-toggle" title="toggle submenu display">
        toggle submenu display
      </button>

      <a href="#">Menu Item 2</a>

      <menu class="submenu">
        <li>
          <a href="#">Submenu Item 2.1</a>
        </li>
        <li>
          <a href="#">Submenu Item 2.2</a>
        </li>
      </menu>
    </li>
  </menu>
</nav>