jQuery : how to debug?
<p>Recently i watched a tutorial from youtube (<a href="http://www.youtube.com/watch?v=8mwKq7%5FJlS8" rel="nofollow">http://www.youtube.com/watch?v=8mwKq7%5FJlS8</a>)</p>

<p>The boy is typing jQuery code and as soon as he presses enter key we can see the result intently. What tool is that?</p>
