DNN handles JavaScript and jQuery very well. In fact, from DNN 5 and onwards jQuery is integrated into the core allowing modules and skins to request jQuery to be included on the page. DNN can be configured to use a hosted or embedded version of jQuery. Your choice of skin and modules will give you full control on what gets rendered in the page output. There is no limit on what kind of pages you can create. 

I am not sure what kind of abstraction level you write about, but I assume you are thinking about the traditional ASP.NET page render - postback - page render thats very common in DotNetNuke modules and ASP.NET WebForm apps in general. But, there is noting in the DotNetNuke framework stopping you from doing things differently.  You have full control on how the page is rendered and how your client server communication will be. The page output is a result of the page skin and modules contributing to the final output. You choose the skin. You choose the modules. You can implement HTTP handlers or page methods/callbacks to handle fine grained ajax communication. The possibilities are endless. Don't be blinded by the usual DotNetNuke module programming tutorials. Look beyond the old school postback style programming. Postbacks are just one way of doing it.