Faceted navigation can cause problems for search engines because they don’t want to crawl and index all of your different sort orders or all your different filtered page versions. They would end up with many different alternatives of your web pages that are not significantly different from a search engine user experience viewpoint.
The main benefit of using JSON and jQuery is that a new URL is not created when a user is on one of your web pages and simultaneously applies a filter or sort order. When you use JSON and jQuery, the entire process happens on the client device without involving your web server.
Ajax allows us to handle sorting, filtering, and pagination. Ajax layer can be used to manage the communications with the web server. Imagine that we have a set of 20 pages; the user has the first page of those 15 pages on their device and then requests a change to the sort order. Ajax requests a fresh set of data from the web server for your site similar to a normal HTML transaction running in a separate thread. The benefit is that the rest of the page can load completely while Ajax is running in parallel in turn improving the perceived performance of the page.