In many ways, AJAX applications follow the REST design principles. Each XMLHttpRequest can be viewed as a REST service request, sent using GET. And the response is often in JSON, a popular response format for REST. (See REST Server Responses, above.)
To make your AJAX application truly RESTful, follow the standard REST design principles (discussed later). You will find that most of them contribute to a good design, even if you don't think of your architecture in terms of REST.