Using the jqXHR object

When an Ajax request is made, jQuery determines the best mechanism available for retrieving the data. This transport could be the standard XMLHttpRequest object, the Microsoft ActiveX XMLHTTP object or a <script> tag.

Because the transport used can vary from request to request, we need a common interface in order to interact with the communication. The jqXHR object provides this interface for us: it is a wrapper for the XMLHttpRequest object when that transport is used, and in other cases, it simulates XMLHttpRequest as best it can. Among the properties and methods it exposes are:

• .responseText or .responseXML containing the returned data

• .status and .statusText containing a status code and description

• .setRequestHeader() to manipulate the HTTP headers sent with the request

• .abort() to prematurely halt the transaction

This jqXHR object is returned from all the jQuery's Ajax methods, so we can store the result if we need access to any of these properties or methods...