Can I use GPL licensed jQuery scripts on the website?
Can I use GPL licensed scripts while generating ad revenue from the page?
Absolutely. The GPL has nothing to do with whether your website - or any application - is for profit or not.
Do I need to provide my sites source to everyone if I use GPL licensed scripts?
But if you are using any kind of minification/obfuscation on the scripts themselves, that might count as modification so you have to at least make sure that you preserve the original licence as it was and that there is a simple way of others to use the scripts, if they choose to. I have no idea what applies when the original author chooses to distribute the scripts in minified versions and you are using them instead of the full ones.
Now if you have modified the scripts themselves in any way, that's a different matter. You absolutely have to make sure that you distribute the modified scripts in a way that's compatible with the GPL - a way that makes it easy for others to use them if they choose to, and distribution via the browser doesn't count.
In that case, I'd probably share the modified source in a public repository, under a compatible license and link to the repository from my site. Think of something like a section in an "about" page that says something like:
This website is made possible by these fine open source projects:
Full source code of my modified version of the jQuery Horizontal Accordion plugin can be found here.
And a collection of smart little scripts I've build, available here.
The last part is not absolutely necessary, you can licence and distribute your own original scripts as you want - but since you already distribute their full source code it'd be nice if you released canonical (non minified/obfuscated) versions of them as open source.
Finally, jQuery core is dual licensed under the MIT Licence and the GPL. So in any case, if you are doing something incompatible with the GPL but compatible with MIT, you are fine. That's for jQuery core, not anything else that has jQuery in its name or is based upon it.
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Disclaimer: Not a lawyer, treat all of the above as guesses. If you can afford it, consult with a lawyer.