Fotiman - 2:18 pm on Jul 9, 2012 (gmt 0)

I don't know about "professional" JavaScript Debuggers... I've never needed more than Firebug [getfirebug.com] for Firefox, or the Chrome Developer Tools (included with Chrome). Both free, both really great tools. IE even comes with a decent Developer Toolbar, and I believe both Safari and Opera also include good debuggers.