title: onchange select box
body: <p>Say we have 2 different select boxes with the same number of options:</p>
  
  <pre><code>&lt;select id="box1"&gt;
  &lt;option value="1" &gt;1&lt;/option&gt;
  &lt;option value="2" &gt;2&lt;/option&gt;
  &lt;/select&gt;
  
  &lt;select id="box2"&gt;
  &lt;option value="3" &gt;3&lt;/option&gt;
  &lt;option value="4" &gt;4&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>Is it possible when we select the first box to select the same option number in the second box automatically? Without jQuery if possible.</p>
  
  <p>UPDATE: the values of 2 boxes are different! When we select the first value of box1 the box 2's value will automatically would be 3! and so on...</p>