title: Get just class names from string selector, jQuery way?
body: <p>Suppose I have string selector such as:</p>
  
  <pre><code>input.js-pretty-select[type="radio"].selected
  </code></pre>
  
  <p>How can I get <strong>just all class names</strong> (<code>js-pretty-select</code> and <code>selected</code>) from this string, possibly using some jQuery core function?</p>
  
  <p>I thought about some regex at first, but then I realized that jQuery might have that already implemented somewhere in it's code, like when resolving selectors with <code>$()</code>.</p>