<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
  </head>
  <body>
    <ul style="list-style-type: none" role="listbox">
      <li
        id="li"
        role="option"
        onclick="this.setAttribute('aria-selected',
          this.getAttribute('aria-selected') == 'true' ? 'false' : 'true')"
      >
        1
      </li>
      <li role="option" aria-selected="false">2</li>
    </ul>
    <li id="outsideSelectable" role="option" tabindex="0">
      outside selectable
    </li>
  </body>
</html>
