title: jquery ui checkbox button state
body: <p>If I have a group of checkbox buttons, what is the correct way to determine the button state?</p>
  
  <p>Right now I do this:</p>
  
  <pre><code>$('#group label').each(function() {
      if ($(this).attr('aria-pressed') == 'true') {
          /* Do something */
      }
  });
  </code></pre>
  
  <p>But sometimes no checkbox buttons are checked and some still have <code>aria-pressed = true</code>.  I don't understand it.</p>