title: in Javascript what does - valuesLength = (values.length , undefined); - do?
body: <p>I am using GWT and the translated javascript has this functionality in several places </p>
  
  <pre><code>valuesLength = (values.length , undefined);
  </code></pre>
  
  <p>I assumed that it was a set to <code>undefined</code> if object does exist but when debugging in the browser although values object exist and length has a value valuesLength always equals undefined.</p>