I am working on ASP.NET Web Forms application. I have a pretty big form with a lot of fields so I want to take as much advantage as possible from the built-in server control
The RequiredFieldValidator from ASP.NET uses jQuery clientside which needs to be registered first (see here).
Apparently, ASP.NET injects a <script> reference to jQuery in the first part of the form.
If you registered your own <script> tags inside of the <head> of your page (first jQuery then jQuery UI), this effectively means you're losing your jQuery UI bindings because jQuery is referenced again after the <head> thanks to WebForms.
The solution is to reference your scripts (jQuery, jQuery UI, and any custom scripts) at the end of the page, for example after the form element.