The most important feature of the Ajax web application architecture is its ability to script HTTP with the XMLHttpRequest object, which was covered in Chapter 20. The X in “Ajax” stands for XML, however, and for many web applications, Ajax’s use of XML-formatted data is its second most important feature.
21.1 Obtaining XML Documents
Chapter 20 showed how to use the XMLHttpRequest object to obtain an XML document from a web server. When the request is complete, the responseXML property of the XMLHttpRequest object refers to a Document object that is the parsed representation of the XML document. This is not the only way to obtain an XML Document object, however. The subsections that follow show how you can create an empty XML document, load an XML document from a URL without using XMLHttpRequest, parse an XML document from a string, and obtain an XML document from an XML data island.