alert should close after 5 seconds
<p>I have simple javascript alert box i want it to close automatically after 5 second.
if possible help please.</p>

<pre><code>&lt;script type="text/javascript"&gt;
function show_alert()
{
alert("Hello! I am an alert box!");
}
&lt;/script&gt;

&lt;input type="button" onclick="show_alert()" value="Show alert box" /&gt;
</code></pre>
