09 April 2002

1. Document Object Model Core

Editors:
Arnaud Le Hors, IBM
Philippe Le Hégaret, W3C
Gavin Nicol, Inso EPS (for DOM Level 1)
Lauren Wood, SoftQuad, Inc. (for DOM Level 1)
Mike Champion, ArborText and Software AG (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 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 2.0] 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/IEC 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 ([OMG IDL]) 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. The DOMUserData type

To ensure interoperability, the DOM specifies the following:

Type Definition DOMUserData

A DOMUserData represents a reference to an application object.


IDL Definition
typedef Object DOMUserData;

Note: Even though the DOM uses the type DOMUserData, bindings may use different types. For example, in Java DOMUserData is bound to the Object type, while in ECMAScript DOMUserData is bound to any type.

Issue DOMKeyObject-1:
What does DOMUserData map to in ECMAScript?
Resolution: "any type"

1.1.8. The DOMObject type

To ensure interoperability, the DOM specifies the following:

Type Definition DOMObject

A DOMObject represents a reference to an application object.


IDL Definition
typedef Object DOMObject;

Note: Even though the DOM uses the type DOMObject, bindings may use different types. For example, in Java and ECMAScript DOMObject is bound to the Object type.

1.1.9. 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.

The W3C Text normalization, as defined in [CharModel], is assumed to happen at serialization time. The DOM Level 3 Load and Save module [DOM Level 3 Abstract Schemas and Load and Save] provides a serialization mechanism (see the DOMWriter interface, section 2.3.1) and defines the "ls-normalize-characters" to assure that text is serialized in the W3C Text Normalization form. Other serialization mechanisms built on top of the DOM Level 3 Core also have to assure that text is serialized in the W3C Text Normalization form.

(ED: We need to review the case sensitivity of methods and attributes and how it fits with XML and HTML. Current wording is not clear at all ... )

1.1.10. XML Namespaces

The DOM Level 2 (and higher) supports XML namespaces [XML 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.

In general, the DOM implementation (and higher) doesn't perform any URI normalization or canonicalization. The URIs given to the DOM are assumed to be valid (e.g., characters such as white spaces 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. Applications that wish to have no namespace should use the value null as the namespaceURI parameter of methods. If they pass an empty string the DOM implementation turns it into a null.

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 [XML 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: Given that the property [in-scope namespaces] defined in [XML Information set] is not accessible from DOM Level 3 Core, the properties [prefix] and [namespace name] defined by the Namespace Information Item in [XML Information set] are not accessible from DOM Level 3 Core. However, [DOM Level 3 XPath] does provide a way to access them.

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.

1.1.11. Mixed DOM implementations

As new XML vocabularies are developed, those defining the vocabularies are also beginning to define specialized APIs for manipulating XML instances of those vocabularies. This is usually done by extending the DOM to provide interfaces and methods that perform operations frequently needed their users. For example, the MathML [MathML 2.0] and SVG [SVG 1.0] specifications are developing DOM extensions to allow users to manipulate instances of these vocabularies using semantics appropriate to images and mathematics (respectively) as well as the generic DOM XML semantics. Instances of SVG or MathML are often embedded in XML documents conforming to a different schema such as XHTML.

While the XML Namespaces Recommendation provides a mechanism for integrating these documents at the syntax level, it has become clear that the DOM Level 2 Recommendation [DOM Level 2 Core] is not rich enough to cover all the issues that have been encountered in having these different DOM implementations be used together in a single application. DOM Level 3 deals with the requirements brought about by embedding fragments written according to a specific markup language (the embedded component) in a document where the rest of the markup is not written according to that specific markup language (the host document). It does not deal with fragments embedded by reference or linking.

A DOM implementation supporting DOM Level 3 Core should be able to collaborate with subcomponents implementing specific DOMs to assemble a compound document that can be traversed and manipulated via DOM interfaces as if it were a seamless whole.

The normal typecast operation on an object should support the interfaces expected by legacy code for a given document type. Typecasting techniques may not be adequate for selecting between multiple DOM specializations of an object which were combined at run time, because they may not all be part of the same object as defined by the binding's object model. Conflicts are most obvious with the Document object, since it is shared as owner by the rest of the document. In a homogeneous document, elements rely on the Document for specialized services and construction of specialized nodes. In a heterogeneous document, elements from different modules expect different services and APIs from the same Document object, since there can only be one owner and root of the document hierarchy.

1.1.12. Bootstrapping

Because previous versions of the DOM specification only defined a set of interfaces, applications had to rely on some implementation dependent code to start from. However, hard-coding the application to a specific implementation prevents the application from running on other implementations and from using the most-suitable implementation of the environment. At the same time, implementations may also need to load modules or perform other setup to efficiently adapt to different and sometimes mutually-exclusive feature sets.

To solve these problems this specification introduces a DOMImplementationRegistry object with a function that lets an application find an implementation, based on the specific features it requires. How this object is found and what it exactly looks like is not defined here, because this cannot be done in a language-independent manner. Instead, each language binding defines its own way of doing this. See Java Language Binding and ECMAScript Language Binding for specifics.

In all cases, though, the DOMImplementationRegistry provides a getDOMImplementation method accepting a features string, which is passed to every known DOMImplementationSource until a suitable DOMImplementation is found and returned. This method is the same as the one found on the DOMImplementationSource interface defined below.

Any number of DOMImplementationSource objects can be registered. A source may return one or more DOMImplementation singletons or construct new DOMImplementation objects, depending upon whether the requested features require specialized state in the DOMImplementation object.

Issue Level-3-Bootstrap-1:
Is this not generic enough?
Resolution: Yes. (F2F 31 Jul 2001)
Issue Level-3-Bootstrap-2:
Should the method getDOMImplementation be called byFeature instead?
Resolution: No. (F2F 31 Jul 2001)

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 "3.0" (respectively) to determine whether or not this module is supported by the implementation. Any implementation that conforms to DOM Level 3 or a DOM Level 3 module must conform to the Core module. Please refer to additional information about conformance in this specification. The DOM Level 3 Core module is backward compatible with the DOM Level 2 Core [DOM Level 2 Core] module, i.e. a DOM Level 3 Core implementation who returns true for "Core" with the version number "3.0" must also return true for this feature when the version number is "2.0", "" or, null.

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 when null was not expected.

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;
// Introduced in DOM Level 3:
const unsigned short      VALIDATION_ERR                 = 16;

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.
VALIDATION_ERR, introduced in DOM Level 3.
If a call to a method such as insertBefore or removeChild would make the Node invalid with respect to "partial validity", this exception would be raised and the operation would not be done. This code is used in [DOM Level 3 Abstract Schemas and Load and Save]. Refer to this specification for further information.
WRONG_DOCUMENT_ERR
If a node is used in a different document than the one that created it (that doesn't support it)
Interface DOMImplementationSource

This interface permits a DOM implementer to supply one or more implementations, based upon requested features. Each implemented DOMImplementationSource object is listed in the binding-specific list of available sources so that its DOMImplementation objects are made available.


IDL Definition

Methods
getDOMImplementation
A method to request a DOM implementation.
Parameters
features of type DOMString
A string that specifies which features are required. This is a space separated list in which each feature is specified by its name optionally followed by a space and a version number. This is something like: "XML 1.0 Traversal Events 2.0"
Return Value

DOMImplementation

An implementation that has the desired features, or null if this source has none.

No Exceptions
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);
  // Introduced in DOM Level 3:
  DOMImplementation  getInterface(in DOMString feature);
};

Methods
createDocument introduced in DOM Level 2
Creates a DOM Document object of the specified type with its document element.
Note that based on the DocumentType given to create the document, the implementation may instantiate specialized Document objects that support additional features than the "Core", such as "HTML" [DOM Level 2 HTML]. On the other hand, setting the DocumentType after the document was created makes this very unlikely to happen. Alternatively, specialized Document creation methods, such as createHTMLDocument [DOM Level 2 HTML], can be used to obtain specific types of Document objects.
Parameters
namespaceURI of type DOMString
The namespace URI of the document element to create or null.
qualifiedName of type DOMString
The qualified name of the document element to be created or null.
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 with its document element. If the NamespaceURI, qualifiedName, and doctype are null, the returned Document is empty with no document element.

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 is null and the namespaceURI is different from null, or if the qualifiedName has a prefix that is "xml" and the namespaceURI is different from "http://www.w3.org/XML/1998/namespace" [XML Namespaces], or if the DOM implementation does not support the "XML" feature but a non-null namespace URI was provided, since namespaces were defined by XML.

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

NOT_SUPPORTED_ERR: May be raised by DOM implementations which do not support the "XML" feature, if they choose not to support this method.

Note: Other features introduced in the future, by the DOM WG or in extensions defined by other groups, may also demand support for this method; please consult the definition of the feature to see if it requires this method.

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.
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.

NOT_SUPPORTED_ERR: May be raised by DOM implementations which do not support the "XML" feature, if they choose not to support this method.

Note: Other features introduced in the future, by the DOM WG or in extensions defined by other groups, may also demand support for this method; please consult the definition of the feature to see if it requires this method.

getInterface introduced in DOM Level 3
This method makes available a DOMImplementation's specialized interface (see Mixed DOM implementations).
Parameters
feature of type DOMString
The name of the feature requested (case-insensitive).
Return Value

DOMImplementation

Returns an alternate DOMImplementation which implements the specialized APIs of the specified feature, if any, or null if there is no alternate DOMImplementation object which implements interfaces associated with that feature. Any alternate DOMImplementation returned by this method must delegate to the primary core DOMImplementation and not return results inconsistent with the primary DOMImplementation

No Exceptions
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 3 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.
version of type DOMString
This is the version number of the feature to test. In Level 3, the string can be either "3.0", "2.0" or "1.0". If the version is null or empty string, 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.

Note: The properties [notations] and [unparsed entities] defined by the Document Information Item in [XML Information set] are accessible through the DocumentType interface. The property [all declarations processed] is not accessible through the DOM API.


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 {
  // Modified in DOM Level 3:
  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);
  // Introduced in DOM Level 3:
           attribute DOMString       actualEncoding;
  // Introduced in DOM Level 3:
           attribute DOMString       encoding;
  // Introduced in DOM Level 3:
           attribute boolean         standalone;
  // Introduced in DOM Level 3:
           attribute DOMString       version;
                                        // raises(DOMException) on setting

  // Introduced in DOM Level 3:
           attribute boolean         strictErrorChecking;
  // Introduced in DOM Level 3:
           attribute DOMErrorHandler errorHandler;
  // Introduced in DOM Level 3:
           attribute DOMString       documentURI;
  // Introduced in DOM Level 3:
  Node               adoptNode(in Node source)
                                        raises(DOMException);
  // Introduced in DOM Level 3:
  void               normalizeDocument();
  // Introduced in DOM Level 3:
  boolean            canSetNormalizationFeature(in DOMString name, 
                                                in boolean state);
  // Introduced in DOM Level 3:
  void               setNormalizationFeature(in DOMString name, 
                                             in boolean state)
                                        raises(DOMException);
  // Introduced in DOM Level 3:
  boolean            getNormalizationFeature(in DOMString name)
                                        raises(DOMException);
  // Introduced in DOM Level 3:
  Node               renameNode(in Node n, 
                                in DOMString namespaceURI, 
                                in DOMString name)
                                        raises(DOMException);
};

Attributes
actualEncoding of type DOMString, introduced in DOM Level 3
An attribute specifying the actual encoding of this document. This is null otherwise.
This attribute represents the property [character encoding scheme] defined in [XML Information set].
doctype of type DocumentType, readonly, modified in DOM Level 3
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.
This provides direct access to the DocumentType node, child node of this Document. This node can be set at document creation time and later changed through the use of child nodes manipulation methods, such as insertBefore, or replaceChild. Note, however, that while some implementations may instantiate different types of Document objects supporting additional features than the "Core", such as "HTML" [DOM Level 2 HTML], based on the DocumentType specified at creation time, changing it afterwards is very unlikely to result in a change of the features supported.
documentElement of type Element, readonly
This is a convenience attribute that allows direct access to the child node that is the document element of the document.
This attribute represents the property [document element] defined in [XML Information set].
documentURI of type DOMString, introduced in DOM Level 3
The location of the document or null if undefined.
Beware that when the Document supports the feature "HTML" [DOM Level 2 HTML], the href attribute of the HTML BASE element takes precedence over this attribute.
encoding of type DOMString, introduced in DOM Level 3
An attribute specifying, as part of the XML declaration, the encoding of this document. This is null when unspecified.
errorHandler of type DOMErrorHandler, introduced in DOM Level 3
This attribute allows applications to specify a DOMErrorHandler to be called in the event that an error is encountered while performing an operation on a document. Note that not all methods use this mechanism, see the description of each method for details.
implementation of type DOMImplementation, readonly
The DOMImplementation object that handles this document. A DOM application may use objects from multiple implementations.
standalone of type boolean, introduced in DOM Level 3
An attribute specifying, as part of the XML declaration, whether this document is standalone.
This attribute represents the property [standalone] defined in [XML Information set].
strictErrorChecking of type boolean, introduced in DOM Level 3
An attribute specifying whether errors checking is enforced or not. When set to false, the implementation is free to not test every possible error case normally defined on DOM operations, and not raise any DOMException. In case of error, the behavior is undefined. This attribute is true by defaults.
version of type DOMString, introduced in DOM Level 3
An attribute specifying, as part of the XML declaration, the version number of this document. This is null when unspecified.
This attribute represents the property [version] defined in [XML Information set].
Exceptions on setting

DOMException

NOT_SUPPORTED_ERR: Raised if the version is set to a value that is not supported by this Document.

Methods
adoptNode introduced in DOM Level 3
Changes the ownerDocument of a node, its children, as well as the attached attribute nodes if there are any. If the node has a parent it is first removed from its parent child list. This effectively allows moving a subtree from one document to another. 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 adopted Attr. The descendants of the source Attr are recursively adopted.
DOCUMENT_FRAGMENT_NODE
The descendants of the source node are recursively adopted.
DOCUMENT_NODE
Document nodes cannot be adopted.
DOCUMENT_TYPE_NODE
DocumentType nodes cannot be adopted.
ELEMENT_NODE
Specified attribute nodes of the source element are adopted, and the generated Attr nodes. Default attributes are discarded, though if the document being adopted into defines default attributes for this element name, those are assigned. The descendants of the source element are recursively adopted.
ENTITY_NODE
Entity nodes cannot be adopted.
ENTITY_REFERENCE_NODE
Only the EntityReference node itself is adopted, the descendants are discarded, 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 cannot be adopted.
PROCESSING_INSTRUCTION_NODE, TEXT_NODE, CDATA_SECTION_NODE, COMMENT_NODE
These nodes can all be adopted. No specifics.
Issue adoptNode-1:
Should this method simply return null when it fails? How "exceptional" is failure for this method?
Resolution: Stick with raising exceptions only in exceptional circumstances, return null on failure (F2F 19 Jun 2000).
Issue adoptNode-2:
Can an entity node really be adopted?
Resolution: No, neither can Notation nodes (Telcon 13 Dec 2000).
Issue adoptNode-3:
Does this affect keys and hashCode's of the adopted subtree nodes?
If so, what about readonly-ness of key and hashCode?
if not, would appendChild affect keys/hashCodes or would it generate exceptions if key's are duplicate?
Resolution: Both keys and hashcodes have been dropped.
Parameters
source of type Node
The node to move into this document.
Return Value

Node

The adopted node, or null if this operation fails, such as when the source node comes from a different implementation.

Exceptions

DOMException

NOT_SUPPORTED_ERR: Raised if the source node is of type DOCUMENT, DOCUMENT_TYPE.

NO_MODIFICATION_ALLOWED_ERR: Raised when the source node is readonly.

canSetNormalizationFeature introduced in DOM Level 3
Query whether setting a feature to a specific value is supported.
The feature name has the same form as a DOM hasFeature string.
Parameters
name of type DOMString
The name of the feature to check.
state of type boolean
The requested state of the feature (true or false).
Return Value

boolean

true if the feature could be successfully set to the specified value, or false if the feature is not recognized or the requested value is not supported. This does not change the current value of the feature itself.

No Exceptions
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.
Per [XML Namespaces], applications must use the value null as the namespaceURI parameter for methods if they wish to have no namespace.
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, per the XML 1.0 specification [XML 1.0].

NAMESPACE_ERR: Raised if the qualifiedName is malformed per the Namespaces in XML specification, 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, or its prefix, is "xmlns" and the namespaceURI is different from "http://www.w3.org/2000/xmlns/".

NOT_SUPPORTED_ERR: Always thrown if the current document does not support the "XML" feature, since namespaces were defined by XML.

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, otherwise it depends on the case-sentivity of the markup language in use. In that case, the name is mapped to the canonical form of that markup 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.
Per [XML Namespaces], applications must use the value null as the namespaceURI parameter for methods if they wish to have no namespace.
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, per the XML 1.0 specification [XML 1.0].

NAMESPACE_ERR: Raised if the qualifiedName is malformed per the Namespaces in XML specification, 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" [XML Namespaces].

NOT_SUPPORTED_ERR: Always thrown if the current document does not support the "XML" feature, since namespaces were defined by XML.

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 document order.
Parameters
tagname of type DOMString
The name of the tag to match on. The special value "*" matches all tags. For XML, this is case-sensitive, otherwise it depends on the case-sentivity of the markup language in use.
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 document order.
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
getNormalizationFeature introduced in DOM Level 3
Look up the value of a feature.
The feature name has the same form as a DOM hasFeature string. The recognized features are the same as the ones defined for setNormalizationFeature.
Parameters
name of type DOMString
The name of the feature to look up.
Return Value

boolean

The current state of the feature (true or false).

Exceptions

DOMException

NOT_FOUND_ERR: Raised when the feature name is not recognized.

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, the source node is not altered. User data associated to the imported node is not carried over. However, if any UserDataHandlers has been specified along with the associated data these handlers will be called with the appropriate parameters before this method returns.
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 DocumentFragment are recursively imported and the resulting nodes reassembled under the imported DocumentFragment 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 this type of nodes since they cannot have any children.
PROCESSING_INSTRUCTION_NODE
The imported node copies its target and data values from those of the source node.
Note that the deep parameter has no effect on this type of nodes since they cannot have any children.
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.
Note that the deep parameter has no effect on these types of nodes since they cannot have any children.
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 nodes that cannot have any children, and on Attr, and EntityReference 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.

INVALID_CHARACTER_ERR: Raised if one the imported names contain an illegal character. This may happen when importing an XML 1.1 [XML 1.1] element into an XML 1.0 document, for instance.

normalizeDocument introduced in DOM Level 3
This method acts as if the document was going through a save and load cycle, putting the document in a "normal" form. The actual result depends on the features being set and governing what operations actually take place. See setNormalizationFeature for details.
Noticeably this method normalizes Text nodes, makes the document "namespace wellformed", according to the algorithm described below in pseudo code, by adding missing namespace declaration attributes and adding or changing namespace prefixes, updates the replacement tree of EntityReference nodes, normalizes attribute values, etc.
Mutation events, when supported, are generated to reflect the changes occuring on the document.
See Namespace normalization for details on how namespace declaration attributes and prefixes are normalized.
Issue normalizeNS-1:
Any other name? Joe proposes normalizeNamespaces.
Resolution: normalizeDocument. (F2F 26 Sep 2001)
Issue normalizeNS-2:
How specific should this be? Should we not even specify that this should be done by walking down the tree?
Resolution: Very. See above.
Issue normalizeNS-3:
What does this do on attribute nodes?
Resolution: Doesn't do anything (F2F 1 Aug 2000).
Issue normalizeNS-4:
How does it work with entity reference subtree which may be broken?
Resolution: This doesn't affect entity references which are not visited in this operation (F2F 1 Aug 2000).
Issue normalizeNS-5:
Should this really be on Node?
Resolution: Yes, but this only works on Document, Element, and DocumentFragment. On other types it is a no-op. (F2F 1 Aug 2000).
No. Now that it does much more than simply fixing namespaces it only makes sense on Document (F2F 26 Sep 2001).
Issue normalizeNS-6:
What happens with read-only nodes?
Issue normalizeNS-7:
What/how errors should be reported? Are there any?
Resolution: Through the error reporter.
Issue normalizeNS-8:
Should this be optional?
Resolution: No.
Issue normalizeNS-9:
What happens with regard to mutation events?
Resolution: Mutation events are fired as expected. (F2F 28 Feb 2002).
No Parameters
No Return Value
No Exceptions
renameNode