7. AJAX and REST

AJAX is a popular web development technique that makes web pages interactive using JavaScript.

In AJAX, requests are sent to the server using XMLHttpRequest objects. The response is used by the JavaScript code to dynamically change the current page.

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.

A later section provides code samples for issuing HTTP requests in JavaScript, but if you've done any AJAX programming, you are already familiar with all that.