The Node interface is the primary datatype for the entire Document Object Model. It represents a single node in the document tree. While all objects implementing the Node interface expose methods for dealing with children, not all objects implementing the Node interface may have children. For example, Text nodes may not have children, and adding children to such nodes results in a DOMException being raised.

The attributes nodeName, nodeValue and attributes are included as a mechanism to get at node information without casting down to the specific derived interface. In cases where there is no obvious mapping of these attributes for a specific nodeType (e.g., nodeValue for an Element or attributes for a Comment), this returns null. Note that the specialized interfaces may contain additional and more convenient mechanisms to get and set the relevant information.

The values of nodeName, nodeValue, and attributes vary according to the node type as follows:

An integer indicating which type of node this is.

The NodeType enumeration has the following constants of type unsigned short.

A bitmask indicating the relative document position of a node with respect to another node.

If the two nodes being compared are the same node, then no flags are set on the return.

Otherwise, the order of two nodes is determined by looking for common containers -- containers which contain both. A node directly contains any child nodes. A node also directly contains any other nodes attached to it such as attributes contained in an element or entities and notations contained in a document type. Nodes contained in contained nodes are also contained, but less-directly as the number of intervening containers increases.

If there is no common container node, then the order is based upon order between the root container of each node that is in no container. In this case, the result is disconnected and implementation-specific. This result is stable as long as these outer-most containing nodes remain in memory and are not inserted into some other containing node. This would be the case when the nodes belong to different documents or fragments, and cloning the document or inserting a fragment might change the order.

If one of the nodes being compared contains the other node, then the container precedes the contained node, and reversely the contained node follows the container. For example, when comparing an element against its own attribute or child, the element node precedes its attribute node and its child node, which both follow it.

If neither of the previous cases apply, then there exists a most-direct container common to both nodes being compared. In this case, the order is determined based upon the two determining nodes directly contained in this most-direct common container that either are or contain the corresponding nodes being compared.

If these two determining nodes are both child nodes, then the natural DOM order of these determining nodes within the containing node is returned as the order of the corresponding nodes. This would be the case, for example, when comparing two child elements of the same element.

If one of the two determining nodes is a child node and the other is not, then the corresponding node of the child node follows the corresponding node of the non-child node. This would be the case, for example, when comparing an attribute of an element with a child element of the same element.

If neither of the two determining node is a child node and one determining node has a greater value of nodeType than the other, then the corresponding node precedes the other. This would be the case, for example, when comparing an entity of a document type against a notation of the same document type.

If neither of the two determining node is a child node and nodeType is the same for both determining nodes, then an implementation-dependent order between the determining nodes is returned. This order is stable as long as no nodes of the same nodeType are inserted into or removed from the direct container. This would be the case, for example, when comparing two attributes of the same element, and inserting or removing additional attributes might change the order between existing attributes.

The DocumentPosition enumeration has the following constants of type unsigned short.

A NamedNodeMap containing the attributes of this node (if it is an Element) or null otherwise.

A NodeList that contains all children of this node. If there are no children, this is a NodeList containing no nodes.

The first child of this node. If there is no such node, this returns null.

The last child of this node. If there is no such node, this returns null.

Returns the local part of the qualified name of this node.

For nodes of any type other than ELEMENT_NODE and ATTRIBUTE_NODE and nodes created with a DOM Level 1 method, such as createElement from the Document interface, this is always null.

The namespace URI of this node, or null if it is unspecified.

This is not a computed value that is the result of a namespace lookup based on an examination of the namespace declarations in scope. It is merely the namespace URI given at creation time.

For nodes of any type other than ELEMENT_NODE and ATTRIBUTE_NODE and nodes created with a DOM Level 1 method, such as createElement from the Document interface, this is always null.

The node immediately following this node. If there is no such node, this returns null.

The name of this node, depending on its type; see the table above.

A code representing the type of the underlying object, as defined above.

The value of this node, depending on its type; see the table above. When it is defined to be null, setting it has no effect. including if the node is read-only.

The Document object associated with this node. This is also the Document object used to create new nodes. When this node is a Document or a DocumentType which is not used with any Document yet, this is null.

The parent of this node. All nodes, except Attr, Document, DocumentFragment, Entity, and Notation may have a parent. However, if a node has just been created and not yet added to the tree, or if it has been removed from the tree, this is null.

The namespace prefix of this node, or null if it is unspecified.

Note that setting this attribute, when permitted, changes the nodeName attribute, which holds the qualified name, as well as the tagName and name attributes of the Element and Attr interfaces, when applicable.

Note also that changing the prefix of an attribute that is known to have a default value, does not make a new attribute with the default value and the original prefix appear, since the namespaceURI and localName do not change.

For nodes of any type other than ELEMENT_NODE and ATTRIBUTE_NODE and nodes created with a DOM Level 1 method, such as createElement from the Document interface, this is always null .

The node immediately preceding this node. If there is no such node, this returns null.

Adds the node newChild to the end of the list of children of this node. If the newChild is already in the tree, it is first removed.

Returns a duplicate of this node, i.e., serves as a generic copy constructor for nodes. The duplicate node has no parent; (parentNode is null.).

Cloning an Element copies all attributes and their values, including those generated by the XML processor to represent defaulted attributes, but this method does not copy any text it contains unless it is a deep clone, since the text is contained in a child Text node. Cloning an Attribute directly, as opposed to be cloned as part of an Element cloning operation, returns a specified attribute (specified is true ). Cloning any other type of node simply returns a copy of this node.

Note that cloning an immutable subtree results in a mutable copy, but the children of an EntityReference clone are readonly. In addition, clones of unspecified Attr nodes are specified. And, cloning Document, DocumentType, Entity, and Notation nodes is implementation dependent.

Compares a node with this node with regard to their position in the document and according to the document order .

Returns whether this node (if it is an element) has any attributes.

Returns whether this node has any children.

Inserts the node newChild before the existing child node refChild. If refChild is null, insert newChild at the end of the list of children.

If newChild is a DocumentFragment object, all of its children are inserted, in the same order, before refChild. If the newChild is already in the tree, it is first removed.

Tests whether the DOM implementation implements a specific feature and that feature is supported by this node.

Look up the namespace URI associated to the given prefix, starting from this node.

Puts all Text nodes in the full depth of the sub-tree underneath this Node, including attribute nodes, into a "normal" form where only structure (e.g., elements, comments, processing instructions, CDATA sections, and entity references) separates Text nodes, i.e., there are neither adjacent Text nodes nor empty Text nodes. This can be used to ensure that the DOM view of a document is the same as if it were saved and re-loaded, and is useful when operations (such as XPointer [XPointer] lookups) that depend on a particular document tree structure are to be used.

Removes the child node indicated by oldChild from the list of children, and returns it.

Replaces the child node oldChild with newChild in the list of children, and returns the oldChild node.

If newChild is a DocumentFragment object, oldChild is replaced by all of the DocumentFragment children, which are inserted in the same order. If the newChild is already in the tree, it is first removed.