Firebug guide

"But how do you trace, track and debug client-side code interactively? The use of alerts has been useful but does not support an interactive way for you to interact with the web-page on the fly. To make matters worse, even if you place some traces into your js code to help find the slow functions, etc, network latency may be another cause of slow response. Or maybe the order your files are loaded is an issue? Or maybe their are caching issues. Well, Firebug to the rescue." - from a more than useful guide for Firebug usage