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Language-Specific DOMs

Property/Method

Type/Return Type Description

nextSibling

Node

Pointer to the next sibling;

null

if this is the last

sibling

hasChildNodes() Boolean

Returns true when

childNodes

contains one or

more nodes

attributes

NamedNodeMap

Contains

Attr

objects representing an element’s

attributes; only used for

Element

nodes

appendChild(

node

) Node

Adds

node

to the end of

childNodes

removeChild(

node

) Node

Removes

node

from

childNodes

replaceChild

Node

Replaces

oldnode

childNodes

with

(

newnode

oldnode

)

newnode

insertBefore

Node

Inserts

newnode

before

refnode

(

newnode

refnode

)

childNodes

In addition to nodes, the DOM also defines some helper objects, which are used to work with nodes but

are not necessarily part of a DOM document:

NodeList

— an array of nodes indexed numerically; used to represent child nodes of an element

NamedNodeMap

— an array of nodes indexed both numerically and name; used to represent ele-

ment attributes

These helper objects provide additional access and traversal methods for dealing with DOM document.

Usage specifics are discussed later.

Language-Specific DOMs

Any XML-based language, such as XHTML and SVG, can make use of the core DOM just introduced

because they are technically XML. However, many languages go on to define their own DOMs that

extend the XML core to provide language-specific features.

Along with developing the XML DOM, the W3C concurrently developed a DOM more specific to

XHTML (and HTML). This DOM defines an

HTMLDocument

and

HTMLElement

as the basis for the imple-

mentation. Each HTML element is represented by its own

HTMLElement

type, such as

HTMLDivElement

representing

<div>

, with the exception of a small subset of elements that don’t require special properties

or methods other than those provided by

HTMLElement

. Throughout the rest of the book, you are intro-

duced to various HTML DOM features as well as to the core XML DOM features.

Regular HTML is not valid XML; however, most modern Web browsers are forgiv-

ing and still parse an HTML document into a proper DOM document (even without

the XML prolog). However, it’s always best to use XHTML code when programming

Web pages to eliminate bad coding habits.

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