XML Objectified: Attributes Considered

Looking back at the pets.xml file you'll notice that the <pet> tag contains an attribute, named name. This provides us with a smooth segue into looking at attributes of an XML element. You already know how to access the node which represents an XML element, but let's say you would like to zoom in on an attribute of an element. Attributes are considered something of a "special case" in the XML DOM because they do not cleanly fit into the parent-child or branch-leaf metaphors. For elements which possess attributes the IDOMElement object contains an attributes list, which is an IDOMNamedNodemap of IDOMAttribute objects, with which you can inspect attributes and their values associated with a particular element.

The following chart of properties and methods illustrates how to access various facets of the attributes list. We're again relying on the ongoing example -- follow along with the pets.xml document and this will make sense.

petbase.childNodes(1).childNodes(0).attributes.length	yields	1
petbase.childNodes(1).childNodes(0).attributes(0).nodeName	yields	"name"
petbase.childNodes(1).childNodes(0).attributes.getNamedItem("name")	yields	"ella dibella"
petbase.childNodes(1).childNodes(0).attributes.item(0)	yields	"ella dibella"

The last two examples in the above table both yield the same result because they both return the value of the same attribute. Note, however, that the getNamedItem() method is preferable, because it guarantees which attribute's value will be returned. There is no guarantee in the XML DOM that all attributes of an element will always be stored in the same index order so you cannot be sure that attribute 0, for instance, will always reflect the name attribute in this case.

XML Objectified: IDOMElement
XML via the Document Object Model: A Preliminary Course
XML Objectified: IDOMElement's Revisited