It's worth noting that while that's OK for desktop visitors, shifting the workflow to the client means you're putting a lot more stress on mobile visitors and resulting in a worse experience for them.

Network performance and latency is all over the place, leaving AJAX an unpredictable mess. On top of that you're adding the overhead of spinning up the javascript runtime on the phone, running the code etc. etc, all of which eats precious battery time for them, and negatively impacts your time to screen, a very important metric.