[ebiester]

Basically, your server side doesn't change much. The difference is that instead of outputting HTML, it outputs JSON.

Instead of writing your own code to handle AJAX on top of jQuery, you write code that handles the real logic and let the framework handle the DOM manipulation. In that way, it's easier to test, easier to debug, easier to provide superior experiences.

Right now, writing AJAX in the browser is equivalent of the JSPs of yesteryear. Remember all that horrific logic that used to creep into your JSPs? That's what jQuery looks like, and this new crop of frameworks is getting us to JSTL or facelets at the minimum.

[gambler]

The difference is that instead of outputting HTML, it outputs JSON.

Which is non-semantic, so it cannot be progressively enhanced, does not benefit from browser updates and is pretty much not crawlable by anyone except Google.