I recently ran into a problem where my web part, that uses jQuery, didn’t work anymore on the SharePoint production server. After some investigation it became clear that it was caused by another SharePoint feature that was enabled on the site.
This SharePoint feature used it’s own JavaScript framework that conflicted with jQuery. jQuery uses some keywords and expressions in a fashion that does not match with other libraries. jQuery Has foreseen this and has functionality in place to resolve this. More information on how to solve this can be found here.
After applying these changes the two frameworks were working happily together.
For more detailed information about the issue I encountered see here.
Hope it helps.
