title: Change src on selection
body: <p>I want to change the src attribute of image according to the selection of drop list menu. For example, the droplist contains "Peter, Henry, David", the image will show different images accordingly to the name (something like peter.png, henry.png, david.png, or 1.png, 2.png, 3.png)
  So here is what I did. However, it didn't work. I don't know what I missed here.</p>
  
  <pre><code>&lt;select id="name" name="name"&gt; 
  &lt;option value=""&gt;Please select...&lt;/option&gt; 
  &lt;option value="Peter"&gt;Peter&lt;/option&gt; 
  &lt;option value="Henry"&gt;Henry&lt;/option&gt; 
  &lt;option value="David"&gt;David&lt;/option&gt; 
  &lt;/select&gt;
  
   &lt;img src="default.png" id="imageholder" alt="imageholder" /&gt;
  
      &lt;script type="text/javascript"&gt;
      $(document).ready(function() {      
          $("#name").change(function() { 
          var nameholder= $("#name").val(); 
          $('#imageholder').attr('src', nameholder + ".png" ); 
          });   
      })  
      &lt;/script&gt;
  </code></pre>