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18.3. Node and Other Generic Interfaces

The Node interface is the DOM Core class hierarchy's root. Though never instantiated directly, it is the root interface of all specific interfaces, and you can use it to extract information from any DOM object without knowing its actual type. It is possible to access a document's complete structure and content using only the methods and properties exposed by the Node interface. As shown in Table 18-1, this interface contains information about the type, location, name, and value of the corresponding underlying document data.

Table 18-1. Node interface

Type

 

Name

Read-only

DOM 2.0

Attributes

       

DOMString

 

nodeName

Figure

 

DOMString

 

nodeValue

   

Short

 

Unsigned type

Figure

 

Node

 

parentNode

Figure

 

NodeList

 

childNodes

Figure

 

Node

 

firstChild

Figure

 

Node

 

lastChild

Figure

 

Node

 

previousSibling

Figure

 

Node

 

nextSibling

Figure

 

NamedNodeMap

 

attributes

Figure

 

Document

 

ownerDocument

Figure

Figure

DOMString

 

namespaceURI

Figure

Figure

DOMString

 

Prefix

 

Figure

DOMString

 

localName

Figure

Figure

Methods

       

Boolean

 

hasAttributes

 

Figure

Node

 

insertBefore

   
 

Node

newChild

   
 

Node

refChild

   

Node

 

replaceChild

   
 

Node

newChild

   
 

Node

oldChild

   

Node

 

removeChild

   
 

Node

oldChild

   

Node

 

appendChild

   
 

Node

newChild

   

Boolean

 

hasChildNodes

   

Node

 

cloneNode

   
 

Boolean

Deep

   

Void

 

normalize

 

Figure

Boolean

 

isSupported

 

Figure

 

DOMString

Feature

 

Figure

 

DOMString

Version

 

Figure

Since the Node interface is never instantiated directly, the nodeType attribute contains a value that indicates the given instance's specific object type. Based on the nodeType, it is possible to cast a generic Node reference safely to a specific interface for further processing. Table 18-2 shows the node type values and their corresponding DOM interfaces, and Table 18-3 shows the values they provide for nodeName, nodeValue, and attributes attributes.

Table 18-2. DOM node types and interfaces

Node type

DOM interface

ATTRIBUTE_NODE

Attr

CDATA_SECTION_NODE

CDATASection

COMMENT_NODE

Comment

DOCUMENT_FRAGMENT_NODE

DocumentFragment

DOCUMENT_NODE

Document

DOCUMENT_TYPE_NODE

DocumentType

ELEMENT_NODE

Element

ENTITY_NODE

Entity

ENTITY_REFERENCE_NODE

EntityReference

NOTATION_NODE

Notation

PROCESSING_INSTRUCTION_NODE

ProcessingInstruction

TEXT_NODE

Text

Table 18-3. DOM node types and method results

Node type

nodeName

nodeValue

Attributes

ATTRIBUTE_NODE

att name

att value

null

CDATA_SECTION_NODE

#cdata-section

content

null

COMMENT_NODE

#comment

content

null

DOCUMENT_FRAGMENT_NODE

#document-fragment

null

null

DOCUMENT_NODE

#document

null

null

DOCUMENT_TYPE_NODE

document type name

null

null

ELEMENT_NODE

tag name

null

NamedNodeMap

ENTITY_NODE

entity name

null

null

ENTITY_REFERENCE_NODE

name of entity referenced

null

null

NOTATION_NODE

notation name

null

null

PROCESSING_INSTRUCTION_NODE

target

content excluding the target

null

TEXT_NODE

#text

content

null

Note that the nodeValue attribute returns the contents of simple text and comment nodes, but returns nothing for elements. Retrieving the text of an element requires inspecting the text nodes it contains.



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