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XML

In the

XMLList

object, methods generally call the method of the same name on each

XML

object in the

list and return the results in another

XMLList

object. For example, if you call

attribute(“id”)

on an

XMLList

object, it calls the

attribute(“id”)

on each

XML

object. If the

XML

object returns an attribute,

that attribute is added to the result

XMLList

object. Once all

XML

objects have contributed, the result

XMLList

object is returned. Here’s a list of all the methods that act this way:

attribute()

— Returns an

XMLList

of the given attribute from all

XML

objects

attributes()

— Returns an

XMLList

of all attributes from all

XML

objects

child()

— Returns an

XMLList

of all child nodes with the given name from all

XML

objects

children()

— Returns an

XMLList

of all child nodes from all

XML

objects

comments()

— Returns an

XMLList

of all child comment nodes from all

XML

objects

descendants()

— Returns an

XMLList

of all descendant nodes from all

XML

objects

elements()

— Returns an

XMLList

of all child elements nodes from all

XML

objects

normalize()

— Normalizes each

XML

object

processingInstructions()

— Returns an

XMLList

of all child processing instruction nodes

from all

XML

objects

text()

— Returns an

XMLList

of all child text nodes from all

XML

objects

The two methods that didn’t make sense for the

XML

object,

length()

and

contains()

, make much

more sense when used in the context of an

XMLList

. The

length()

method returns the number of

objects in the

XMLList

; the

contains()

method determines if a given XML object is contained within

the

XMLList

, for example:

var oXml1 = <name>Nicholas C. Zakas</name>;

var oXml2 = <name>Michael Smith</name>;

var oXmlList = oXml1 + oXml2;

alert(oXmlList.contains(oXml1)); //outputs “true”

In this example,

oXmlList

is created by combining

oXml1

and

oXml2

, so when the

contains()

method

is called with

oXml1

, the result is

true

Four other methods behave somewhat differently from the

XML

object:

copy()

— Returns an exact duplicate of the

XMLList

object

hasComplexContent()

— Returns

true

when the

XMLList

contains one element with com-

plex content or when the

XMLList

contains more than one

XML

object

hasSimpleContent()

— Returns

true

when the

XMLList

is empty and when the

XMLList

contains one

XML

object with simple content

parent()

— Returns an

XML

object if all objects in the

XMLList

have the same parent; other-

wise returns

undefined

Together, the

XML

and

XMLList

classes provide a very powerful interface to manipulate XML data.

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The Evolution of JavaScript

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