E4X is ECMAscript for XML, a simple syntax that integrates XML into JavaScript and offers many (but not all) functions from DOM and XPath. It is fully supported by Firefox.

•  http://en.wikipedia.org/wiki/ECMAScript_for_XML
•  http://mooshup.com/docs/e4xquickstart.html
•  https://developer.mozilla.org/en/E4X