토글을 위한 aria-expanded 및 aria-controls

<button aria-expanded="false" aria-controls="menu">
  Menu
</button>
<ul id="menu" hidden>
  <li><a href="/">Home</a></li>
</ul>
<script>
btn.addEventListener('click', () => {
  const expanded = btn.getAttribute('aria-expanded') === 'true';
  btn.setAttribute('aria-expanded', !expanded);
  menu.hidden = expanded;
});
</script>

<button
  id="details-btn"
  aria-expanded="false"
  aria-controls="details-panel"
>
  Show Details
</button>
<div id="details-panel" hidden>
  <p>Additional details go here...</p>
</div>
<!-- Screen reader: 'Show Details, button, collapsed'
     After click: 'Show Details, button, expanded' -->

<div class="accordion">
  <h3>
    <button
      aria-expanded="false"
      aria-controls="panel-1"
    >Section 1</button>
  </h3>
  <div id="panel-1" hidden>
    <p>Panel 1 content...</p>
  </div>

  <h3>
    <button
      aria-expanded="false"
      aria-controls="panel-2"
    >Section 2</button>
  </h3>
  <div id="panel-2" hidden>
    <p>Panel 2 content...</p>
  </div>
</div>

<nav>
  <button
    aria-expanded="false"
    aria-haspopup="true"
    aria-controls="products-menu"
  >Products</button>

  <ul id="products-menu" role="menu" hidden>
    <li role="menuitem"><a href="/widget">Widget</a></li>
    <li role="menuitem"><a href="/gadget">Gadget</a></li>
  </ul>
</nav>

<button aria-haspopup="menu">File</button>
<!-- Values: true (menu), menu, listbox, tree, grid, dialog -->
<!-- Screen reader: 'File, button, has popup' -->

<!-- Note: aria-haspopup="true" is equivalent to "menu" -->
<!-- Use specific values when the popup type matters -->

<details>
  <summary>FAQ Question</summary>
  <p>Answer goes here.</p>
</details>
<!-- Browser automatically provides aria-expanded
     and the disclosure widget semantics -->
<!-- No need to add aria-expanded manually to summary -->

/* Panel hidden by default: */
[aria-controls] + [hidden] {
  display: none;
}

/* Or using aria-expanded on the button: */
[aria-expanded="false"] + .panel {
  display: none;
}

[aria-expanded="true"] + .panel {
  display: block;
}

/* Rotate arrow icon: */
[aria-expanded="true"] .arrow {
  transform: rotate(180deg);
}

// Accordion: focus stays on the button (usually OK)
// Dropdown menu: move focus to first menu item on open

button.addEventListener('click', () => {
  const expanded = button.getAttribute('aria-expanded') === 'true';
  button.setAttribute('aria-expanded', !expanded);
  panel.hidden = expanded;

  if (!expanded) {
    // Opening a dropdown: focus first item
    panel.querySelector('a, button, [tabindex]')?.focus();
  }
});