title: Get all ID of input box that contains a class
body: <p>How can i get the ID of an input box that contains a certain class value</p>
  
  <p><em>ex:</em></p>
  
  <pre><code>&lt;input id="first" class="failed" /&gt;
  &lt;input id="last" class="failed" /&gt;
  &lt;input id="city" class="failed" /&gt;
  &lt;input id="state" class="failed" /&gt;
  </code></pre>
  
  <p>I want to alert all the ID that contains the class failed after pushing a button or a command.</p>