how to swap image on clicking on image?
<p>Here I use two images. when i click once on the Sort_down.png image then it changes to Sort_up.png. 
When I click on this image again it is not changing back to Sort_down.png, how can I achieve this ?</p>

<pre><code> &lt;script type="text/javascript"&gt;
function clkimg() {
        var img = document.getElementById('stCodeDSC');
                img.src = '../Images/sort_up.png';

        }
  &lt;/script&gt;


    &lt;td width="11%" bgcolor="#C5DEFF" class="menu_header"&gt;
    &lt;div align="center" onclick="clkimg();" &gt; 
    &lt;img name="stCodeDSC"  class="img" src="../Images/Sort_down.png"  id="stCodeDSC"&gt;
  &lt;/div&gt;
 &lt;/td&gt;
</code></pre>
