jQuery is an awesome javascript library and using it in our extensions has meant that on the whole there are very few javascript conflicts. We run JQuery in no conflict mode so it will play nicely with mootools and the other popular js libraries.

One issue exists however and is the source of a majority of our javascript related support requests. If you load jQuery more than once in your site you will get errors.

So basically if your template includes jQuery and then another component, module or plugin also includes jQuery then you will more than likely get an error on your site and the given script will stop working. As a workaround we developed the JB library which loads jQuery automatically in the head of the template above all of the other scripts so we can now include javascripts in the template itself or on the fly in the module.

If you are using jce utilities you may have the experience where jQuery ois loaded twice even if you are using the JB library. The work around is to unpublish the JB library plugin and let the JCE version of the jQuery library do all of the work.

How can you tell if jQuery is being loaded twice?
In firefox click on view source and do a search for the string jQuery. If you find that jquery-1.2.6 or any other version number is already being loaded then you need to figure out how to remove the extra redundant references.