13 November, 2000

1. Document Object Model Core

Editors
Arnaud Le Hors, IBM
Gavin Nicol, Inso EPS (for DOM Level 1)
Lauren Wood, SoftQuad, Inc. (for DOM Level 1)
Mike Champion, ArborText (for DOM Level 1 from November 20, 1997)
Steve Byrne, JavaSoft (for DOM Level 1 until November 19, 1997)

Table of contents

1.1. Overview of the DOM Core Interfaces

This section defines a set of objects and interfaces for accessing and manipulating document objects. The functionality specified in this section (the Core functionality) is sufficient to allow software developers and web script authors to access and manipulate parsed HTML and XML content inside conforming products. The DOM Core API also allows creation and population of a Document object using only DOM API calls; loading a Document and saving it persistently is left to the product that implements the DOM API.

1.1.1. The DOM Structure Model

The DOM presents documents as a hierarchy of Node objects that also implement other, more specialized interfaces. Some types of nodes may have child nodes of various types, and others are leaf nodes that cannot have anything below them in the document structure. For XML and HTML, the node types, and which node types they may have as children, are as follows:

The DOM also specifies a NodeList interface to handle ordered lists of Nodes, such as the children of a Node, or the elements returned by the getElementsByTagName method of the Element interface, and also a NamedNodeMap interface to handle unordered sets of nodes referenced by their name attribute, such as the attributes of an Element. NodeList and NamedNodeMap objects in the DOM are live; that is, changes to the underlying document structure are reflected in all relevant NodeList and NamedNodeMap objects. For example, if a DOM user gets a NodeList object containing the children of an Element, then subsequently adds more children to that element (or removes children, or modifies them), those changes are automatically reflected in the NodeList, without further action on the user's part. Likewise, changes to a Node in the tree are reflected in all references to that Node in NodeList and NamedNodeMap objects.

Finally, the interfaces Text, Comment, and CDATASection all inherit from the CharacterData interface.

1.1.2. Memory Management

Most of the APIs defined by this specification are interfaces rather than classes. That means that an implementation need only expose methods with the defined names and specified operation, not implement classes that correspond directly to the interfaces. This allows the DOM APIs to be implemented as a thin veneer on top of legacy applications with their own data structures, or on top of newer applications with different class hierarchies. This also means that ordinary constructors (in the Java or C++ sense) cannot be used to create DOM objects, since the underlying objects to be constructed may have little relationship to the DOM interfaces. The conventional solution to this in object-oriented design is to define factory methods that create instances of objects that implement the various interfaces. Objects implementing some interface "X" are created by a "createX()" method on the Document interface; this is because all DOM objects live in the context of a specific Document.

The DOM Level 2 API does not define a standard way to create DOMImplementation objects; DOM implementations must provide some proprietary way of bootstrapping these DOM interfaces, and then all other objects can be built from there.

The Core DOM APIs are designed to be compatible with a wide range of languages, including both general-user scripting languages and the more challenging languages used mostly by professional programmers. Thus, the DOM APIs need to operate across a variety of memory management philosophies, from language bindings that do not expose memory management to the user at all, through those (notably Java) that provide explicit constructors but provide an automatic garbage collection mechanism to automatically reclaim unused memory, to those (especially C/C++) that generally require the programmer to explicitly allocate object memory, track where it is used, and explicitly free it for re-use. To ensure a consistent API across these platforms, the DOM does not address memory management issues at all, but instead leaves these for the implementation. Neither of the explicit language bindings defined by the DOM API (for ECMAScript and Java) require any memory management methods, but DOM bindings for other languages (especially C or C++) may require such support. These extensions will be the responsibility of those adapting the DOM API to a specific language, not the DOM Working Group.

1.1.3. Naming Conventions

While it would be nice to have attribute and method names that are short, informative, internally consistent, and familiar to users of similar APIs, the names also should not clash with the names in legacy APIs supported by DOM implementations. Furthermore, both OMG IDL and ECMAScript have significant limitations in their ability to disambiguate names from different namespaces that make it difficult to avoid naming conflicts with short, familiar names. So, DOM names tend to be long and descriptive in order to be unique across all environments.

The Working Group has also attempted to be internally consistent in its use of various terms, even though these may not be common distinctions in other APIs. For example, the DOM API uses the method name "remove" when the method changes the structural model, and the method name "delete" when the method gets rid of something inside the structure model. The thing that is deleted is not returned. The thing that is removed may be returned, when it makes sense to return it.

1.1.4. Inheritance vs. Flattened Views of the API

The DOM Core APIs present two somewhat different sets of interfaces to an XML/HTML document: one presenting an "object oriented" approach with a hierarchy of inheritance, and a "simplified" view that allows all manipulation to be done via the Node interface without requiring casts (in Java and other C-like languages) or query interface calls in COM environments. These operations are fairly expensive in Java and COM, and the DOM may be used in performance-critical environments, so we allow significant functionality using just the Node interface. Because many other users will find the inheritance hierarchy easier to understand than the "everything is a Node" approach to the DOM, we also support the full higher-level interfaces for those who prefer a more object-oriented API.

In practice, this means that there is a certain amount of redundancy in the API. The Working Group considers the "inheritance" approach the primary view of the API, and the full set of functionality on Node to be "extra" functionality that users may employ, but that does not eliminate the need for methods on other interfaces that an object-oriented analysis would dictate. (Of course, when the O-O analysis yields an attribute or method that is identical to one on the Node interface, we don't specify a completely redundant one.) Thus, even though there is a generic nodeName attribute on the Node interface, there is still a tagName attribute on the Element interface; these two attributes must contain the same value, but the it is worthwhile to support both, given the different constituencies the DOM API must satisfy.

1.1.5. The DOMString type

To ensure interoperability, the DOM specifies the following:

  • Type Definition DOMString

    A DOMString is a sequence of 16-bit units.


    IDL Definition
    valuetype DOMString sequence<unsigned short>;
    

  • Applications must encode DOMString using UTF-16 (defined in [Unicode] and Amendment 1 of [ISO/IEC 10646]).
    The UTF-16 encoding was chosen because of its widespread industry practice. Note that for both HTML and XML, the document character set (and therefore the notation of numeric character references) is based on UCS [ISO-10646]. A single numeric character reference in a source document may therefore in some cases correspond to two 16-bit units in a DOMString (a high surrogate and a low surrogate).

    Note: Even though the DOM defines the name of the string type to be DOMString, bindings may use different names. For example for Java, DOMString is bound to the String type because it also uses UTF-16 as its encoding.

Note: As of August 2000, the OMG IDL specification ([OMGIDL]) included a wstring type. However, that definition did not meet the interoperability criteria of the DOM API since it relied on negotiation to decide the width and encoding of a character.

1.1.6. The DOMTimeStamp type

To ensure interoperability, the DOM specifies the following:

  • Type Definition DOMTimeStamp

    A DOMTimeStamp represents a number of milliseconds.


    IDL Definition
    typedef unsigned long long DOMTimeStamp;
    

  • Note: Even though the DOM uses the type DOMTimeStamp, bindings may use different types. For example for Java, DOMTimeStamp is bound to the long type. In ECMAScript, TimeStamp is bound to the Date type because the range of the integer type is too small.

1.1.7. String comparisons in the DOM

The DOM has many interfaces that imply string matching. HTML processors generally assume an uppercase (less often, lowercase) normalization of names for such things as elements, while XML is explicitly case sensitive. For the purposes of the DOM, string matching is performed purely by binary comparison of the 16-bit units of the DOMString. In addition, the DOM assumes that any case normalizations take place in the processor, before the DOM structures are built.

Note: Besides case folding, there are additional normalizations that can be applied to text. The W3C I18N Working Group is in the process of defining exactly which normalizations are necessary, and where they should be applied. The W3C I18N Working Group expects to require early normalization, which means that data read into the DOM is assumed to already be normalized. The DOM and applications built on top of it in this case only have to assure that text remains normalized when being changed. For further details, please see [Charmod].

1.1.8. XML Namespaces

The DOM Level 2 supports XML namespaces [Namespaces] by augmenting several interfaces of the DOM Level 1 Core to allow creating and manipulating elements and attributes associated to a namespace.

As far as the DOM is concerned, special attributes used for declaring XML namespaces are still exposed and can be manipulated just like any other attribute. However, nodes are permanently bound to namespace URIs as they get created. Consequently, moving a node within a document, using the DOM, in no case results in a change of its namespace prefix or namespace URI. Similarly, creating a node with a namespace prefix and namespace URI, or changing the namespace prefix of a node, does not result in any addition, removal, or modification of any special attributes for declaring the appropriate XML namespaces. Namespace validation is not enforced; the DOM application is responsible. In particular, since the mapping between prefixes and namespace URIs is not enforced, in general, the resulting document cannot be serialized naively. For example, applications may have to declare every namespace in use when serializing a document.

DOM Level 2 doesn't perform any URI normalization or canonicalization. The URIs given to the DOM are assumed to be valid (e.g., characters such as whitespaces are properly escaped), and no lexical checking is performed. Absolute URI references are treated as strings and compared literally. How relative namespace URI references are treated is undefined. To ensure interoperability only absolute namespace URI references (i.e., URI references beginning with a scheme name and a colon) should be used. Note that because the DOM does no lexical checking, the empty string will be treated as a real namespace URI in DOM Level 2 methods. Applications must use the value null as the namespaceURI parameter for methods if they wish to have no namespace.

Note: In the DOM, all namespace declaration attributes are by definition bound to the namespace URI: "http://www.w3.org/2000/xmlns/". These are the attributes whose namespace prefix or qualified name is "xmlns". Although, at the time of writing, this is not part of the XML Namespaces specification [Namespaces], it is planned to be incorporated in a future revision.

In a document with no namespaces, the child list of an EntityReference node is always the same as that of the corresponding Entity. This is not true in a document where an entity contains unbound namespace prefixes. In such a case, the descendants of the corresponding EntityReference nodes may be bound to different namespace URIs, depending on where the entity references are. Also, because, in the DOM, nodes always remain bound to the same namespace URI, moving such EntityReference nodes can lead to documents that cannot be serialized. This is also true when the DOM Level 1 method createEntityReference of the Document interface is used to create entity references that correspond to such entities, since the descendants of the returned EntityReference are unbound. The DOM Level 2 does not support any mechanism to resolve namespace prefixes. For all of these reasons, use of such entities and entity references should be avoided or used with extreme care. A future Level of the DOM may include some additional support for handling these.

The new methods, such as createElementNS and createAttributeNS of the Document interface, are meant to be used by namespace aware applications. Simple applications that do not use namespaces can use the DOM Level 1 methods, such as createElement and createAttribute. Elements and attributes created in this way do not have any namespace prefix, namespace URI, or local name.

Note: DOM Level 1 methods are namespace ignorant. Therefore, while it is safe to use these methods when not dealing with namespaces, using them and the new ones at the same time should be avoided. DOM Level 1 methods solely identify attribute nodes by their nodeName. On the contrary, the DOM Level 2 methods related to namespaces, identify attribute nodes by their namespaceURI and localName. Because of this fundamental difference, mixing both sets of methods can lead to unpredictable results. In particular, using setAttributeNS, an element may have two attributes (or more) that have the same nodeName, but different namespaceURIs. Calling getAttribute with that nodeName could then return any of those attributes. The result depends on the implementation. Similarly, using setAttributeNode, one can set two attributes (or more) that have different nodeNames but the same prefix and namespaceURI. In this case getAttributeNodeNS will return either attribute, in an implementation dependent manner. The only guarantee in such cases is that all methods that access a named item by its nodeName will access the same item, and all methods which access a node by its URI and local name will access the same node. For instance, setAttribute and setAttributeNS affect the node that getAttribute and getAttributeNS, respectively, return.

1.2. Fundamental Interfaces

The interfaces within this section are considered fundamental, and must be fully implemented by all conforming implementations of the DOM, including all HTML DOM implementations [DOM Level 2 HTML], unless otherwise specified.

A DOM application may use the hasFeature(feature, version) method of the DOMImplementation interface with parameter values "Core" and "2.0" (respectively) to determine whether or not this module is supported by the implementation. Any implementation that conforms to DOM Level 2 or a DOM Level 2 module must conform to the Core module. Please refer to additional information about conformance in this specification.

Exception DOMException

DOM operations only raise exceptions in "exceptional" circumstances, i.e., when an operation is impossible to perform (either for logical reasons, because data is lost, or because the implementation has become unstable). In general, DOM methods return specific error values in ordinary processing situations, such as out-of-bound errors when using NodeList.

Implementations should raise other exceptions under other circumstances. For example, implementations should raise an implementation-dependent exception if a null argument is passed.

Some languages and object systems do not support the concept of exceptions. For such systems, error conditions may be indicated using native error reporting mechanisms. For some bindings, for example, methods may return error codes similar to those listed in the corresponding method descriptions.


IDL Definition
exception DOMException {
  unsigned short   code;
};
// ExceptionCode
const unsigned short      INDEX_SIZE_ERR                 = 1;
const unsigned short      DOMSTRING_SIZE_ERR             = 2;
const unsigned short      HIERARCHY_REQUEST_ERR          = 3;
const unsigned short      WRONG_DOCUMENT_ERR             = 4;
const unsigned short      INVALID_CHARACTER_ERR          = 5;
const unsigned short      NO_DATA_ALLOWED_ERR            = 6;
const unsigned short      NO_MODIFICATION_ALLOWED_ERR    = 7;
const unsigned short      NOT_FOUND_ERR                  = 8;
const unsigned short      NOT_SUPPORTED_ERR              = 9;
const unsigned short      INUSE_ATTRIBUTE_ERR            = 10;
// Introduced in DOM Level 2:
const unsigned short      INVALID_STATE_ERR              = 11;
// Introduced in DOM Level 2:
const unsigned short      SYNTAX_ERR                     = 12;
// Introduced in DOM Level 2:
const unsigned short      INVALID_MODIFICATION_ERR       = 13;
// Introduced in DOM Level 2:
const unsigned short      NAMESPACE_ERR                  = 14;
// Introduced in DOM Level 2:
const unsigned short      INVALID_ACCESS_ERR             = 15;

Definition group ExceptionCode

An integer indicating the type of error generated.

Note: Other numeric codes are reserved for W3C for possible future use.

Defined Constants
DOMSTRING_SIZE_ERR
If the specified range of text does not fit into a DOMString
HIERARCHY_REQUEST_ERR
If any node is inserted somewhere it doesn't belong
INDEX_SIZE_ERR
If index or size is negative, or greater than the allowed value
INUSE_ATTRIBUTE_ERR
If an attempt is made to add an attribute that is already in use elsewhere
INVALID_ACCESS_ERR, introduced in DOM Level 2.
If a parameter or an operation is not supported by the underlying object.
INVALID_CHARACTER_ERR
If an invalid or illegal character is specified, such as in a name. See production 2 in the XML specification for the definition of a legal character, and production 5 for the definition of a legal name character.
INVALID_MODIFICATION_ERR, introduced in DOM Level 2.
If an attempt is made to modify the type of the underlying object.
INVALID_STATE_ERR, introduced in DOM Level 2.
If an attempt is made to use an object that is not, or is no longer, usable.
NAMESPACE_ERR, introduced in DOM Level 2.
If an attempt is made to create or change an object in a way which is incorrect with regard to namespaces.
NOT_FOUND_ERR
If an attempt is made to reference a node in a context where it does not exist
NOT_SUPPORTED_ERR
If the implementation does not support the requested type of object or operation.
NO_DATA_ALLOWED_ERR
If data is specified for a node which does not support data
NO_MODIFICATION_ALLOWED_ERR
If an attempt is made to modify an object where modifications are not allowed
SYNTAX_ERR, introduced in DOM Level 2.
If an invalid or illegal string is specified.
WRONG_DOCUMENT_ERR
If a node is used in a different document than the one that created it (that doesn't support it)
Interface DOMImplementation

The DOMImplementation interface provides a number of methods for performing operations that are independent of any particular instance of the document object model.


IDL Definition
interface DOMImplementation {
  boolean            hasFeature(in DOMString feature, 
                                in DOMString version);
  // Introduced in DOM Level 2:
  DocumentType       createDocumentType(in DOMString qualifiedName, 
                                        in DOMString publicId, 
                                        in DOMString systemId)
                                        raises(DOMException);
  // Introduced in DOM Level 2:
  Document           createDocument(in DOMString namespaceURI, 
                                    in DOMString qualifiedName, 
                                    in DocumentType doctype)
                                        raises(DOMException);
};

Methods
createDocument introduced in DOM Level 2
Creates an XML Document object of the specified type with its document element. HTML-only DOM implementations do not need to implement this method.
Parameters
namespaceURI of type DOMString
The namespace URI of the document element to create.
qualifiedName of type DOMString
The qualified name of the document element to be created.
doctype of type DocumentType
The type of document to be created or null.
When doctype is not null, its Node.ownerDocument attribute is set to the document being created.
Return Value

Document

A new Document object.

Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified qualified name contains an illegal character.

NAMESPACE_ERR: Raised if the qualifiedName is malformed, if the qualifiedName has a prefix and the namespaceURI is null, or if the qualifiedName has a prefix that is "xml" and the namespaceURI is different from "http://www.w3.org/XML/1998/namespace" [Namespaces].

WRONG_DOCUMENT_ERR: Raised if doctype has already been used with a different document or was created from a different implementation.

createDocumentType introduced in DOM Level 2
Creates an empty DocumentType node. Entity declarations and notations are not made available. Entity reference expansions and default attribute additions do not occur. It is expected that a future version of the DOM will provide a way for populating a DocumentType.
HTML-only DOM implementations do not need to implement this method.
Parameters
qualifiedName of type DOMString
The qualified name of the document type to be created.
publicId of type DOMString
The external subset public identifier.
systemId of type DOMString
The external subset system identifier.
Return Value

DocumentType

A new DocumentType node with Node.ownerDocument set to null.

Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified qualified name contains an illegal character.

NAMESPACE_ERR: Raised if the qualifiedName is malformed.

hasFeature
Test if the DOM implementation implements a specific feature.
Parameters
feature of type DOMString
The name of the feature to test (case-insensitive). The values used by DOM features are defined throughout the DOM Level 2 specifications and listed in the Conformance section. The name must be an XML name. To avoid possible conflicts, as a convention, names referring to features defined outside the DOM specification should be made unique by reversing the name of the Internet domain name of the person (or the organization that the person belongs to) who defines the feature, component by component, and using this as a prefix. For instance, the W3C SVG Working Group defines the feature "org.w3c.dom.svg".
version of type DOMString
This is the version number of the feature to test. In Level 2, the string can be either "2.0" or "1.0". If the version is not specified, supporting any version of the feature causes the method to return true.
Return Value

boolean

true if the feature is implemented in the specified version, false otherwise.

No Exceptions
Interface DocumentFragment

DocumentFragment is a "lightweight" or "minimal" Document object. It is very common to want to be able to extract a portion of a document's tree or to create a new fragment of a document. Imagine implementing a user command like cut or rearranging a document by moving fragments around. It is desirable to have an object which can hold such fragments and it is quite natural to use a Node for this purpose. While it is true that a Document object could fulfill this role, a Document object can potentially be a heavyweight object, depending on the underlying implementation. What is really needed for this is a very lightweight object. DocumentFragment is such an object.

Furthermore, various operations -- such as inserting nodes as children of another Node -- may take DocumentFragment objects as arguments; this results in all the child nodes of the DocumentFragment being moved to the child list of this node.

The children of a DocumentFragment node are zero or more nodes representing the tops of any sub-trees defining the structure of the document. DocumentFragment nodes do not need to be well-formed XML documents (although they do need to follow the rules imposed upon well-formed XML parsed entities, which can have multiple top nodes). For example, a DocumentFragment might have only one child and that child node could be a Text node. Such a structure model represents neither an HTML document nor a well-formed XML document.

When a DocumentFragment is inserted into a Document (or indeed any other Node that may take children) the children of the DocumentFragment and not the DocumentFragment itself are inserted into the Node. This makes the DocumentFragment very useful when the user wishes to create nodes that are siblings; the DocumentFragment acts as the parent of these nodes so that the user can use the standard methods from the Node interface, such as insertBefore and appendChild.


IDL Definition
interface DocumentFragment : Node {
};

Interface Document

The Document interface represents the entire HTML or XML document. Conceptually, it is the root of the document tree, and provides the primary access to the document's data.

Since elements, text nodes, comments, processing instructions, etc. cannot exist outside the context of a Document, the Document interface also contains the factory methods needed to create these objects. The Node objects created have a ownerDocument attribute which associates them with the Document within whose context they were created.


IDL Definition
interface Document : Node {
  readonly attribute DocumentType     doctype;
  readonly attribute DOMImplementation  implementation;
  readonly attribute Element          documentElement;
  Element            createElement(in DOMString tagName)
                                        raises(DOMException);
  DocumentFragment   createDocumentFragment();
  Text               createTextNode(in DOMString data);
  Comment            createComment(in DOMString data);
  CDATASection       createCDATASection(in DOMString data)
                                        raises(DOMException);
  ProcessingInstruction createProcessingInstruction(in DOMString target, 
                                                    in DOMString data)
                                        raises(DOMException);
  Attr               createAttribute(in DOMString name)
                                        raises(DOMException);
  EntityReference    createEntityReference(in DOMString name)
                                        raises(DOMException);
  NodeList           getElementsByTagName(in DOMString tagname);
  // Introduced in DOM Level 2:
  Node               importNode(in Node importedNode, 
                                in boolean deep)
                                        raises(DOMException);
  // Introduced in DOM Level 2:
  Element            createElementNS(in DOMString namespaceURI, 
                                     in DOMString qualifiedName)
                                        raises(DOMException);
  // Introduced in DOM Level 2:
  Attr               createAttributeNS(in DOMString namespaceURI, 
                                       in DOMString qualifiedName)
                                        raises(DOMException);
  // Introduced in DOM Level 2:
  NodeList           getElementsByTagNameNS(in DOMString namespaceURI, 
                                            in DOMString localName);
  // Introduced in DOM Level 2:
  Element            getElementById(in DOMString elementId);
};

Attributes
doctype of type DocumentType, readonly
The Document Type Declaration (see DocumentType) associated with this document. For HTML documents as well as XML documents without a document type declaration this returns null. The DOM Level 2 does not support editing the Document Type Declaration. docType cannot be altered in any way, including through the use of methods inherited from the Node interface, such as insertNode or removeNode.
documentElement of type Element, readonly
This is a convenience attribute that allows direct access to the child node that is the root element of the document. For HTML documents, this is the element with the tagName "HTML".
implementation of type DOMImplementation, readonly
The DOMImplementation object that handles this document. A DOM application may use objects from multiple implementations.
Methods
createAttribute
Creates an Attr of the given name. Note that the Attr instance can then be set on an Element using the setAttributeNode method.
To create an attribute with a qualified name and namespace URI, use the createAttributeNS method.
Parameters
name of type DOMString
The name of the attribute.
Return Value

Attr

A new Attr object with the nodeName attribute set to name, and localName, prefix, and namespaceURI set to null. The value of the attribute is the empty string.

Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character.

createAttributeNS introduced in DOM Level 2
Creates an attribute of the given qualified name and namespace URI. HTML-only DOM implementations do not need to implement this method.
Parameters
namespaceURI of type DOMString
The namespace URI of the attribute to create.
qualifiedName of type DOMString
The qualified name of the attribute to instantiate.
Return Value

Attr

A new Attr object with the following attributes:

Attribute Value
Node.nodeName qualifiedName
Node.namespaceURI namespaceURI
Node.prefix prefix, extracted from qualifiedName, or null if there is no prefix
Node.localName local name, extracted from qualifiedName
Attr.name qualifiedName
Node.nodeValue the empty string
Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified qualified name contains an illegal character.

NAMESPACE_ERR: Raised if the qualifiedName is malformed, if the qualifiedName has a prefix and the namespaceURI is null, if the qualifiedName has a prefix that is "xml" and the namespaceURI is different from "http://www.w3.org/XML/1998/namespace", or if the qualifiedName is "xmlns" and the namespaceURI is different from "http://www.w3.org/2000/xmlns/".

createCDATASection
Creates a CDATASection node whose value is the specified string.
Parameters
data of type DOMString
The data for the CDATASection contents.
Return Value

CDATASection

The new CDATASection object.

Exceptions

DOMException

NOT_SUPPORTED_ERR: Raised if this document is an HTML document.

createComment
Creates a Comment node given the specified string.
Parameters
data of type DOMString
The data for the node.
Return Value

Comment

The new Comment object.

No Exceptions
createDocumentFragment
Creates an empty DocumentFragment object.
Return Value
No Parameters
No Exceptions
createElement
Creates an element of the type specified. Note that the instance returned implements the Element interface, so attributes can be specified directly on the returned object.
In addition, if there are known attributes with default values, Attr nodes representing them are automatically created and attached to the element.
To create an element with a qualified name and namespace URI, use the createElementNS method.
Parameters
tagName of type DOMString
The name of the element type to instantiate. For XML, this is case-sensitive. For HTML, the tagName parameter may be provided in any case, but it must be mapped to the canonical uppercase form by the DOM implementation.
Return Value

Element

A new Element object with the nodeName attribute set to tagName, and localName, prefix, and namespaceURI set to null.

Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character.

createElementNS introduced in DOM Level 2
Creates an element of the given qualified name and namespace URI. HTML-only DOM implementations do not need to implement this method.
Parameters
namespaceURI of type DOMString
The namespace URI of the element to create.
qualifiedName of type DOMString
The qualified name of the element type to instantiate.
Return Value

Element

A new Element object with the following attributes:

Attribute Value
Node.nodeName qualifiedName
Node.namespaceURI namespaceURI
Node.prefix prefix, extracted from qualifiedName, or null if there is no prefix
Node.localName local name, extracted from qualifiedName
Element.tagName qualifiedName
Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified qualified name contains an illegal character.

NAMESPACE_ERR: Raised if the qualifiedName is malformed, if the qualifiedName has a prefix and the namespaceURI is null, or if the qualifiedName has a prefix that is "xml" and the namespaceURI is different from "http://www.w3.org/XML/1998/namespace" [Namespaces].

createEntityReference
Creates an EntityReference object. In addition, if the referenced entity is known, the child list of the EntityReference node is made the same as that of the corresponding Entity node.

Note: If any descendant of the Entity node has an unbound namespace prefix, the corresponding descendant of the created EntityReference node is also unbound; (its namespaceURI is null). The DOM Level 2 does not support any mechanism to resolve namespace prefixes.

Parameters
name of type DOMString
The name of the entity to reference.
Return Value
Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character.

NOT_SUPPORTED_ERR: Raised if this document is an HTML document.

createProcessingInstruction
Creates a ProcessingInstruction node given the specified name and data strings.
Parameters
target of type DOMString
The target part of the processing instruction.
data of type DOMString
The data for the node.
Return Value
Exceptions

DOMException

INVALID_CHARACTER_ERR: Raised if the specified target contains an illegal character.

NOT_SUPPORTED_ERR: Raised if this document is an HTML document.

createTextNode
Creates a Text node given the specified string.
Parameters
data of type DOMString
The data for the node.
Return Value

Text

The new Text object.

No Exceptions
getElementById introduced in DOM Level 2
Returns the Element whose ID is given by elementId. If no such element exists, returns null. Behavior is not defined if more than one element has this ID.

Note: The DOM implementation must have information that says which attributes are of type ID. Attributes with the name "ID" are not of type ID unless so defined. Implementations that do not know whether attributes are of type ID or not are expected to return null.

Parameters
elementId of type DOMString
The unique id value for an element.
Return Value

Element

The matching element.

No Exceptions
getElementsByTagName
Returns a NodeList of all the Elements with a given tag name in the order in which they are encountered in a preorder traversal of the Document tree.
Parameters
tagname of type DOMString
The name of the tag to match on. The special value "*" matches all tags.
Return Value

NodeList

A new NodeList object containing all the matched Elements.

No Exceptions
getElementsByTagNameNS introduced in DOM Level 2
Returns a NodeList of all the Elements with a given local name and namespace URI in the order in which they are encountered in a preorder traversal of the Document tree.
Parameters
namespaceURI of type DOMString
The namespace URI of the elements to match on. The special value "*" matches all namespaces.
localName of type DOMString
The local name of the elements to match on. The special value "*" matches all local names.
Return Value

NodeList

A new NodeList object containing all the matched Elements.

No Exceptions
importNode introduced in DOM Level 2
Imports a node from another document to this document. The returned node has no parent; (parentNode is null). The source node is not altered or removed from the original document; this method creates a new copy of the source node.
For all nodes, importing a node creates a node object owned by the importing document, with attribute values identical to the source node's nodeName and nodeType, plus the attributes related to namespaces (prefix, localName, and namespaceURI). As in the cloneNode operation on a Node, the source node is not altered.
Additional information is copied as appropriate to the nodeType, attempting to mirror the behavior expected if a fragment of XML or HTML source was copied from one document to another, recognizing that the two documents may have different DTDs in the XML case. The following list describes the specifics for each type of node.
ATTRIBUTE_NODE
The ownerElement attribute is set to null and the specified flag is set to true on the generated Attr. The descendants of the source Attr are recursively imported and the resulting nodes reassembled to form the corresponding subtree.
Note that the deep parameter has no effect on Attr nodes; they always carry their children with them when imported.
DOCUMENT_FRAGMENT_NODE
If the deep option was set to true, the descendants of the source element are recursively imported and the resulting nodes reassembled to form the corresponding subtree. Otherwise, this simply generates an empty DocumentFragment.
DOCUMENT_NODE
Document nodes cannot be imported.
DOCUMENT_TYPE_NODE
DocumentType nodes cannot be imported.
ELEMENT_NODE
Specified attribute nodes of the source element are imported, and the generated Attr nodes are attached to the generated Element. Default attributes are not copied, though if the document being imported into defines default attributes for this element name, those are assigned. If the importNode deep parameter was set to true, the descendants of the source element are recursively imported and the resulting nodes reassembled to form the corresponding subtree.
ENTITY_NODE
Entity nodes can be imported, however in the current release of the DOM the DocumentType is readonly. Ability to add these imported nodes to a DocumentType will be considered for addition to a future release of the DOM.
On import, the publicId, systemId, and notationName attributes are copied. If a deep import is requested, the descendants of the the source Entity are recursively imported and the resulting nodes reassembled to form the corresponding subtree.
ENTITY_REFERENCE_NODE
Only the EntityReference itself is copied, even if a deep import is requested, since the source and destination documents might have defined the entity differently. If the document being imported into provides a definition for this entity name, its value is assigned.
NOTATION_NODE
Notation nodes can be imported, however in the current release of the DOM the DocumentType is readonly. Ability to add these imported nodes to a DocumentType will be considered for addition to a future release of the DOM.
On import, the publicId and systemId attributes are copied.
Note that the deep parameter has no effect on Notation nodes since they never have any children.
PROCESSING_INSTRUCTION_NODE
The imported node copies its target and data values from those of the source node.
TEXT_NODE, CDATA_SECTION_NODE, COMMENT_NODE
These three types of nodes inheriting from CharacterData copy their data and length attributes from those of the source node.
Parameters
importedNode of type Node
The node to import.
deep of type boolean
If true, recursively import the subtree under the specified node; if false, import only the node itself, as explained above. This has no effect on Attr, EntityReference, and Notation nodes.
Return Value

Node

The imported node that belongs to this Document.

Exceptions

DOMException

NOT_SUPPORTED_ERR: Raised if the type of node being imported is not supported.

Interface Node

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.


IDL Definition
interface Node {

  // NodeType
  const unsigned short      ELEMENT_NODE                   = 1;
  const unsigned short      ATTRIBUTE_NODE                 = 2;
  const unsigned short      TEXT_NODE                      = 3;
  const unsigned short      CDATA_SECTION_NODE             = 4;
  const unsigned short      ENTITY_REFERENCE_NODE          = 5;
  const unsigned short      ENTITY_NODE                    = 6;
  const unsigned short      PROCESSING_INSTRUCTION_NODE    = 7;
  const unsigned short      COMMENT_NODE                   = 8;
  const unsigned short      DOCUMENT_NODE                  = 9;
  const unsigned short      DOCUMENT_TYPE_NODE             = 10;
  const unsigned short      DOCUMENT_FRAGMENT_NODE         = 11;
  const unsigned short      NOTATION_NODE                  = 12;

  readonly attribute DOMString        nodeName;
           attribute DOMString        nodeValue;
                                        // raises(DOMException) on setting
                                        // raises(DOMException) on retrieval

  readonly attribute unsigned short   nodeType;
  readonly attribute Node             parentNode;
  readonly attribute NodeList         childNodes;
  readonly attribute Node             firstChild;
  readonly attribute Node             lastChild;
  readonly attribute Node             previousSibling;
  readonly attribute Node             nextSibling;
  readonly attribute NamedNodeMap     attributes;
  // Modified in DOM Level 2:
  readonly attribute Document         ownerDocument;
  Node               insertBefore(in Node newChild, 
                                  in Node refChild)
                                        raises(DOMException);
  Node               replaceChild(in Node newChild, 
                                  in Node oldChild)
                                        raises(DOMException);
  Node               removeChild(in Node oldChild)
                                        raises(DOMException);
  Node               appendChild(in Node newChild)
                                        raises(DOMException);
  boolean            hasChildNodes();
  Node               cloneNode(in boolean deep);
  // Modified in DOM Level 2:
  void               normalize();
  // Introduced in DOM Level 2:
  boolean            isSupported(in DOMString feature, 
                                 in DOMString version);
  // Introduced in DOM Level 2:
  readonly attribute DOMString        namespaceURI;
  // Introduced in DOM Level 2:
           attribute DOMString        prefix;
                                        // raises(DOMException) on setting

  // Introduced in DOM Level 2:
  readonly attribute DOMString        localName;
  // Introduced in DOM Level 2:
  boolean            hasAttributes();
};

Definition group NodeType

An integer indicating which type of node this is.

Note: Numeric codes up to 200 are reserved to W3C for possible future use.

Defined Constants
ATTRIBUTE_NODE
The node is an Attr.
CDATA_SECTION_NODE
The node is a CDATASection.
COMMENT_NODE
The node is a Comment.
DOCUMENT_FRAGMENT_NODE
The node is a DocumentFragment.
DOCUMENT_NODE
The node is a Document.
DOCUMENT_TYPE_NODE
The node is a DocumentType.
ELEMENT_NODE
The node is an Element.
ENTITY_NODE
The node is an Entity.
ENTITY_REFERENCE_NODE
The node is an EntityReference.
NOTATION_NODE
The node is a Notation.
PROCESSING_INSTRUCTION_NODE
The node is a ProcessingInstruction.
TEXT_NODE
The node is a Text node.

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

Interface nodeName nodeValue attributes
Attr name of attribute value of attribute null
CDATASection #cdata-section content of the CDATA Section null
Comment #comment content of the comment null
Document #document null null
DocumentFragment #document-fragment null null
DocumentType document type name null null
Element tag name null NamedNodeMap
Entity entity name null null
EntityReference name of entity referenced null null
Notation notation name null null
ProcessingInstruction target entire content excluding the target null
Text #text content of the text node null
Attributes
attributes of type NamedNodeMap, readonly
A NamedNodeMap containing the attributes of this node (if it is an Element) or null otherwise.
childNodes of type NodeList, readonly
A NodeList that contains all children of this node. If there are no children, this is a NodeList containing no nodes.
firstChild of type Node, readonly
The first child of this node. If there is no such node, this returns null.
lastChild of type Node, readonly
The last child of this node. If there is no such node, this returns null.
localName of type DOMString, readonly, introduced in DOM Level 2
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.
namespaceURI of type DOMString, readonly, introduced in DOM Level 2
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.

Note: Per the Namespaces in XML Specification [Namespaces] an attribute does not inherit its namespace from the element it is attached to. If an attribute is not explicitly given a namespace, it simply has no namespace.

nextSibling of type Node, readonly
The node immediately following this node. If there is no such node, this returns null.
nodeName of type DOMString, readonly
The name of this node, depending on its type; see the table above.
nodeType of type unsigned short, readonly
A code representing the type of the underlying object, as defined above.
nodeValue of type DOMString
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.
Exceptions on setting

DOMException

NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.

Exceptions on retrieval

DOMException

DOMSTRING_SIZE_ERR: Raised when it would return more characters than fit in a DOMString variable on the implementation platform.

ownerDocument of type Document, readonly, modified in DOM Level 2
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.
parentNode of type Node, readonly
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.
prefix of type DOMString, introduced in DOM Level 2
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.
Exceptions on setting

DOMException

INVALID_CHARACTER_ERR: Raised if the specified prefix contains an illegal character.

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

NAMESPACE_ERR: Raised if the specified prefix is malformed, if the namespaceURI of this node is null, if the specified prefix is "xml" and the namespaceURI of this node is different from "http://www.w3.org/XML/1998/namespace", if this node is an attribute and the specified prefix is "xmlns" and the namespaceURI of this node is different from "http://www.w3.org/2000/xmlns/", or if this node is an attribute and the qualifiedName of this node is "xmlns" [Namespaces].

previousSibling of type Node, readonly
The node immediately preceding this node. If there is no such node, this returns null.
Methods
appendChild
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.
Parameters
newChild of type Node
The node to add.
If it is a DocumentFragment object, the entire contents of the document fragment are moved into the child list of this node
Return Value

Node

The node added.

Exceptions

DOMException

HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to append is one of this node's ancestors.

WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

cloneNode
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.
Parameters
deep of type boolean
If true, recursively clone the subtree under the specified node; if false, clone only the node itself (and its attributes, if it is an Element).
Return Value

Node

The duplicate node.

No Exceptions
hasAttributes introduced in DOM Level 2
Returns whether this node (if it is an element) has any attributes.
Return Value

boolean

true if this node has any attributes, false otherwise.

No Parameters
No Exceptions
hasChildNodes
Returns whether this node has any children.
Return Value

boolean

true if this node has any children, false otherwise.

No Parameters
No Exceptions
insertBefore
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.
Parameters
newChild of type Node
The node to insert.
refChild of type Node
The reference node, i.e., the node before which the new node must be inserted.
Return Value

Node

The node being inserted.

Exceptions

DOMException

HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to insert is one of this node's ancestors.

WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly or if the parent of the node being inserted is readonly.

NOT_FOUND_ERR: Raised if refChild is not a child of this node.

isSupported introduced in DOM Level 2
Tests whether the DOM implementation implements a specific feature and that feature is supported by this node.
Parameters
feature of type DOMString
The name of the feature to test. This is the same name which can be passed to the method hasFeature on DOMImplementation.
version of type DOMString
This is the version number of the feature to test. In Level 2, version 1, this is the string "2.0". If the version is not specified, supporting any version of the feature will cause the method to return true.
Return Value

boolean

Returns true if the specified feature is supported on this node, false otherwise.

No Exceptions
normalize modified in DOM Level 2
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.

Note: In cases where the document contains CDATASections, the normalize operation alone may not be sufficient, since XPointers do not differentiate between Text nodes and CDATASection nodes.

No Parameters
No Return Value
No Exceptions
removeChild
Removes the child node indicated by oldChild from the list of children, and returns it.
Parameters
oldChild of type Node
The node being removed.
Return Value

Node

The node removed.

Exceptions

DOMException

NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.

NOT_FOUND_ERR: Raised if oldChild is not a child of this node.

replaceChild
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.
Parameters
newChild of type Node
The new node to put in the child list.
oldChild of type Node
The node being replaced in the list.
Return Value

Node

The node replaced.

Exceptions

DOMException

HIERARCHY_REQUEST_ERR: Raised if this node is of a type that does not allow children of the type of the newChild node, or if the node to put in is one of this node's ancestors.

WRONG_DOCUMENT_ERR: Raised if newChild was created from a different document than the one that created this node.

NO_MODIFICATION_ALLOWED_ERR: Raised if this node or the parent of the new node is readonly.

NOT_FOUND_ERR: Raised if oldChild is not a child of this node.

Interface NodeList

The NodeList interface provides the abstraction of an ordered collection of nodes, without defining or constraining how this collection is implemented. NodeList objects in the DOM are live.

The items in the NodeList are accessible via an integral index, starting from 0.


IDL Definition
interface NodeList {
  Node               item(in unsigned long index);
  readonly attribute unsigned long    length;
};

Attributes
length of type unsigned long, readonly
The number of nodes in the list. The range of valid child node indices is 0 to length-1 inclusive.
Methods
item
Returns the indexth item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null.
Parameters
index of type unsigned long
Index into the collection.
Return Value

Node

The node at the indexth position in the NodeList, or null if that is not a valid index.

No Exceptions
Interface NamedNodeMap

Objects implementing the NamedNodeMap interface are used to represent collections of nodes that can be accessed by name. Note that NamedNodeMap does not inherit from NodeList; NamedNodeMaps are not maintained in any particular order. Objects contained in an object implementing NamedNodeMap may also be accessed by an ordinal index, but this is simply to allow convenient enumeration of the contents of a NamedNodeMap, and does not imply that the DOM specifies an order to these Nodes.

NamedNodeMap objects in the DOM are live.


IDL Definition
interface NamedNodeMap {
  Node               getNamedItem(in DOMString name);
  Node               setNamedItem(in Node arg)
                                        raises(DOMException);
  Node               removeNamedItem(in DOMString name)
                                        raises(DOMException);
  Node               item(in unsigned long index);
  readonly attribute unsigned long    length;
  // Introduced in DOM Level 2:
  Node               getNamedItemNS(in DOMString namespaceURI, 
                                    in DOMString localName);
  // Introduced in DOM Level 2:
  Node               setNamedItemNS(in Node arg)
                                        raises(DOMException);
  // Introduced in DOM Level 2:
  Node               removeNamedItemNS(in DOMString namespaceURI, 
                                       in DOMString localName)
                                        raises(DOMException);
};

Attributes
length of type unsigned long, readonly
The number of nodes in this map. The range of valid child node indices is 0 to length-1 inclusive.
Methods
getNamedItem
Retrieves a node specified by name.
Parameters
name of type DOMString
The nodeName of a node to retrieve.
Return Value

Node

A Node (of any type) with the specified nodeName, or null if it does not identify any node in this map.

No Exceptions
getNamedItemNS introduced in DOM Level 2
Retrieves a node specified by local name and namespace URI. HTML-only DOM implementations do not need to implement this method.
Parameters
namespaceURI of type DOMString
The namespace URI of the node to retrieve.
localName of type DOMString
The local name of the node to retrieve.
Return Value

Node

A Node (of any type) with the specified local name and namespace URI, or null if they do not identify any node in this map.

No Exceptions
item
Returns the indexth item in the map. If index is greater than or equal to the number of nodes in this map, this returns null.
Parameters
index of type unsigned long
Index into this map.
Return Value

Node

The node at the indexth position in the map, or null if that is not a valid index.

No Exceptions
removeNamedItem
Removes a node specified by name. When this map contains the attributes attached to an element, if the removed attribute is known to have a default value, an attribute immediately appears containing the default value as well as the corresponding namespace URI, local name, and prefix when applicable.
Parameters
name of type DOMString
The nodeName of the node to remove.
Return Value

Node

The node removed from this map if a node with such a name exists.

Exceptions

DOMException

NOT_FOUND_ERR: Raised if there is no node named name in this map.

NO_MODIFICATION_ALLOWED_ERR: Raised if this map is readonly.

removeNamedItemNS introduced in DOM Level 2
Removes a node specified by local name and namespace URI. A removed attribute may be known to have a default value when this map contains the attributes attached to an element, as returned by the attributes attribute of the Node interface. If so, an attribute immediately appears containing the default value as well as the corresponding namespace URI, local name, and prefix when applicable.
HTML-only DOM implementations do not need to implement this method.
Parameters
namespaceURI of type DOMString
The namespace URI of the node to remove.
localName of type DOMString
The local name of the node to remove.
Return Value

Node

The node removed from this map if a node with such a local name and namespace URI exists.

Exceptions