All objects in a DOM document tree (including the Document object itself) implement the Node interface, which provides basic methods for traversing and manipulating the tree.

getParentNode( ) and getChildNodes( ) allow you to traverse up and down the document tree. You can enumerate the children of a given node by looping through the elements of the NodeList returned by getChildNodes( ), or by using getFirstChild( ) and getNextSibling( ) (or getLastChild( ) and getPreviousSibling( ) to loop backwards). It is sometimes useful to call hasChildNodes( ) to determine whether a node has children or not. getOwnerDocument( ) returns the Document node of which the node is a descendant or with which it is associated. It provides a quick way to jump to the root of the document tree.

Several methods allow you to add children to a tree or alter the list of children. appendChild( ) adds a new child node at the end of this nodes list of children. insertChild( ) inserts a node into this nodes list of children, placing it immediately before a specified child node. removeChild( ) removes the specified node from this node's list of children. replaceChild( ) replaces one child node of this node with another node. For all of these methods, if the node to be appended or inserted is already part of the document tree, it is first removed from its current parent. Use cloneNode( ) to produce a copy of this node. Pass true if you want all descendants of this node to be cloned as well.

Every object in a document tree implements the Node interface, but also implements a more specialized subinterface, such as Element or Text. The getNodeType( ) method provides an easy way to determine which subinterface a node implements: the return value is one of the _NODE constants defined by this class. You might use the return value of getNodeType( ) in a switch statement, for exmaple, to determine how to process a node of unknown type.

getNodeName( ) and getNodeValue( ) provide additional information about a node, but the interpretation of the strings they return depends on the node type as shown in the table below. Note that subinterfaces typically define specialized methods (such as the getTagName( ) method of Element and the getdata( ) method of Text) for obtaining this same information. Note also that unless a node is read-only, you can use setNodeValue( ) to alter the value associated with the node.

In documents that use namespaces, the getNodeName( ) method of a Element or Attr node returns the qualified node name, which may include a namespace prefix. In documents that use namespaces, you may prefer to use the namespace-aware methods getNamespaceURI( ), getLocalName( ) and getPrefix( ).

Element nodes may have a list of attributes, and the Element interface defines a number of methods for working with these attributes. In addition, however, Node defines the hasAttributes( ) method to determine if a node has any attributes. If it does, they can be retrieved with getAttributes( ).

Text content in an XML document is represented by Text nodes, which have methods for manipulating that textual content. The Node interface defines a normalize( ) method which has the specialized purpose of normalizing all descendants of a node by deleting empty Text nodes and coalescing adjacent Text nodes into a single combined node. Document trees usually start off in this normalized form, but modifications to the tree may result in non-normalized documents.

Most of the other interfaces in this package extend Node. Document, Element and Text are the most commonly used.

public interface Node {
// Public Constants
     public static final short ATTRIBUTE_NODE;                           =2
     public static final short CDATA_SECTION_NODE;                       =4
     public static final short COMMENT_NODE;                             =8
     public static final short DOCUMENT_FRAGMENT_NODE;                   =11
     public static final short DOCUMENT_NODE;                            =9
5.0  public static final short DOCUMENT_POSITION_CONTAINED_BY;       =16
5.0  public static final short DOCUMENT_POSITION_CONTAINS;           =8
5.0  public static final short DOCUMENT_POSITION_DISCONNECTED;       =1
5.0  public static final short DOCUMENT_POSITION_FOLLOWING;          =4
5.0  public static final short DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC;     =32
5.0  public static final short DOCUMENT_POSITION_PRECEDING;          =2
     public static final short DOCUMENT_TYPE_NODE;                       =10
     public static final short ELEMENT_NODE;                             =1
     public static final short ENTITY_NODE;                              =6
     public static final short ENTITY_REFERENCE_NODE;                    =5
     public static final short NOTATION_NODE;                            =12
     public static final short PROCESSING_INSTRUCTION_NODE;              =7
     public static final short TEXT_NODE;                                =3
// Public Instance Methods
     Node appendChild(Node newChild) throws DOMException;  
     Node cloneNode(boolean deep);  
5.0  short compareDocumentPosition(Node other) throws DOMException;  
     NamedNodeMap getAttributes( );  
5.0  String getBaseURI( );  
     NodeList getChildNodes( );  
5.0  Object getFeature(String feature, String version);  
     Node getFirstChild( );  
     Node getLastChild( );  
     String getLocalName( );  
     String getNamespaceURI( );  
     Node getNextSibling( );  
     String getNodeName( );  
     short getNodeType( );  
     String getNodeValue( ) throws DOMException;  
     Document getOwnerDocument( );  
     Node getParentNode( );  
     String getPrefix( );  
     Node getPreviousSibling( );  
5.0  String getTextContent( ) throws DOMException;  
5.0  Object getUserData(String key);  
     boolean hasAttributes( );  
     boolean hasChildNodes( );  
     Node insertBefore(Node newChild, Node refChild) throws DOMException;  
5.0  boolean isDefaultNamespace(String namespaceURI);  
5.0  boolean isEqualNode(Node arg);  
5.0  boolean isSameNode(Node other);  
     boolean isSupported(String feature, String version);  
5.0  String lookupNamespaceURI(String prefix);  
5.0  String lookupPrefix(String namespaceURI);  
     void normalize( );  
     Node removeChild(Node oldChild) throws DOMException;  
     Node replaceChild(Node newChild, Node oldChild) throws DOMException;  
     void setNodeValue(String nodeValue) throws DOMException;  
     void setPrefix(String prefix) throws DOMException;  
5.0  void setTextContent(String textContent) throws DOMException;  
5.0  Object setUserData(String key, Object data, UserDataHandler handler);  
}