title: cash-dom check if option selected
body: <p>When I'm trying to check an options is selected using by <a href="https://www.npmjs.com/package/cash-dom" rel="nofollow noreferrer">cash-dom</a>, it throws an error like following:</p>
  <blockquote>
  <p>Uncaught DOMException: Element.mozMatchesSelector: ':selected' is not a valid selector</p>
  </blockquote>
  <p>This is my code:</p>
  <pre class="lang-js prettyprint-override"><code>const options = cash('option');
  options.map(i=&gt;{
    console.log(i,options.eq(i));
    console.info(options.eq(i).is(':selected'))
  })
  </code></pre>