title: jquery - select class elements and add to array
body: <p>I want to select all the elements with the class "play" and add them into array "esArreglo".</p>
  
  <p>html file:</p>
  
  <pre><code>&lt;td id="b1" class&gt;&lt;/td&gt;
  &lt;td id="b2" class&gt;&lt;/td&gt;
  &lt;td id="b3" class="play"&gt;&lt;/td&gt;
  &lt;td id="b4" class="play"&gt;&lt;/td&gt;
  </code></pre>
  
  <p>code:</p>
  
  <pre><code>$('td.play').each(function() {
      notas.push(this.id)};
  
  var esArreglo = notas.join(',');
  </code></pre>
  
  <p>How can I fix this?
  Thanks.</p>