get value of an attribute of the clicked element
<pre><code>&lt;ul id='langs'&gt;
   &lt;li data-val='en'&gt;english&lt;/li&gt;
   &lt;li data-val='fr'&gt;francais&lt;/li&gt;
   &lt;li data-val='it'&gt;italiano&lt;/li&gt;
&lt;/ul&gt;
</code></pre>

<p>when the user clicks on any of these <code>&lt;li&gt;</code> I want to <code>alert()</code> it's data-val attribute value</p>

<p>anybody knows how?</p>
