jQuery Lint – James Padolsey
http://james.padolsey.com/javascript/jquery-lint/

It works over the top of jQuery and diligently reports errors and any incorrect usage of jQuery. It will also, to some extent, offer guidance on best practices and performance concerns. Handy with firebug's console.

"jQuery Lint is a simple script you can download and use with jQuery. It works over the top of jQuery and diligently reports errors and any incorrect usage of jQuery. It will also, to some extent, offer guidance on best practices and performance concerns."