How to Debug Your jQuery Code

Firebug—Although many developers have used Firebug, I don’t think that many understand the true potential of its debugging capabilities. If you know your tools inside out, you can become a more productive and efficient programmer. Note: If you aren’t using Firefox, the Firebug Lite bookmarklet can come in handy to provide many of the nice debugging features of its Firefox add-on counterpart. I tend to use this bookmarklet primarily with Google Chrome.
FireQuery—This Firefox Firebug add-on provides some nice features to Firebug, such as letting you see which jQuery events are attached to what DOM elements, displaying any data elements that are attached to a DOM element, and providing the ability to inject jQuery into Web pages that don’t have it already loaded.
FireFinder—This Firefox Firebug add-on can help you find the selector you are looking for. You can test the selector you have, and it will highlight all those items on your Web page.
(Link: How to Debug Your jQuery Code)