The past few months I’ve had the opportunity to work on the new JSON REST API for WordPres. My biggest contribution as a WP API team member has been the Backbone client.
The JSON REST API’s Backbone client let’s you interact with a WordPress installation using Backbone.js collections and models. The client is an extremely useful tool in creating reactive web applications (which seems to be where the web is heading).
As a proof of concept, I created a WordPress starter theme based on Automattic’s _s named _s_backbone. Loops (or post streams) in _s_backbone are driven by Backbone.js collections. This means that posts are grabbed on the fly without a page reload. Pagination is accomplished through a “more” button which, again, does not require a page reload. This is commonly referred to as “infinite scroll”.
Edit: Check out the WP Tavern article on _s_backbone.