AJAX response XML

The most important advantage of XML is that it's the most easily readable format for other humans. A secondary advantage is that XML has been around for quite a while and that many developers are already accustomed to it.
responseText returns the HTTP response as a string.
responseXML returns the response as XML.
The ResponseXML property returns an XML document object, which can be examined and parsed using the DOM.
A web page can fetch information from a database with AJAX technology. The selected data from the database can be converted to an XML document, and then the DOM can be used to extract the values to be displayed.
The following example might look equal to the "PHP AJAX and MySQL" example in the previous chapter. However, there is a big difference: this time we get the data from the PHP page as XML, with the responseXML function. Receiving the response as an XML document allows us to update this page several places, instead of just receiving an HTML output, and displaying it.

AJAX Suggest
AJAX Live Search
PHP Include