previous   next   contents   index

09 June 2003

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

This specification defines a set of objects and interfaces for accessing and manipulating document objects. The functionality specified (the Core functionality) is sufficient to allow software developers and web script authors to access and manipulate parsed HTML [HTML 4.01] and XML [XML 1.0] content inside conforming products. The DOM Core API also allows creation and population of a Document object using only DOM API calls. A solution for loading a Document and saving it persistently is proposed in [DOM Level 3 Load and Save].

1.1 Overview of the DOM Core Interfaces

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 Element.getElementsByTagNameNS(namespaceURI, localName) method, 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 [OMG IDL] and ECMAScript [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 Node.nodeName attribute on the Node interface, there is still a Element.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.

1.2 Primitive types

To ensure interoperability, this specification specifies the following primitive types used in various DOM modules. Even though the DOM uses the primitive types in the interfaces, bindings may use different types and normative bindings are only given for Java and ECMAScript in this specification.

1.2.1 The DOMString type

The DOMString type is used to store [Unicode] characters as a code unit string as defined in section 3.4 of [CharModel]. Applications must encode the characters using UTF-16 as defined in [Unicode] and Amendment 1 of [ISO/IEC 10646].

Type Definition DOMString

A DOMString is a sequence of 16-bit units.


IDL Definition
valuetype DOMString sequence<unsigned short>;

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). For issues related to string comparisons, refer to String comparisons in the DOM.

For Java and ECMAScript, DOMString is bound to the String type because both languages also use UTF-16 as their 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.

1.2.2 The DOMTimeStamp type

The DOMTimeStamp type is used to store an absolute or relative time.

Type Definition DOMTimeStamp

A DOMTimeStamp represents a number of milliseconds.


IDL Definition
typedef unsigned long long DOMTimeStamp;

For Java, DOMTimeStamp is bound to the long type. For ECMAScript, DOMTimeStamp is bound to the Date type because the range of the integer type is too small.

1.2.3 The DOMUserData type

The DOMUserData type is used to store an application data.

Type Definition DOMUserData

A DOMUserData represents a reference to an application data.


IDL Definition
typedef any DOMUserData;

For Java, DOMUserData is bound to the Object type. For ECMAScript, DOMUserData is bound to any type.

1.2.4 The DOMObject type

The DOMUserData type is used to store an application object.

Type Definition DOMObject

A DOMObject represents a reference to an application object.


IDL Definition
typedef Object DOMObject;

For Java and ECMAScript, DOMObject is bound to the Object type.

1.3 General considerations

1.3.1 String comparisons in the DOM

The DOM has many interfaces that imply string matching. For XML, string comparisons are case-sensitive and performed with a binary comparison of the 16-bit units of the DOMStrings. However, for case-insensitive markup languages, such as HTML 4.01 or earlier, these comparisons are case-insensitive where appropriate.

Note that HTML processors often perform specific case normalizations (canonicalization) of the markup before the DOM structures are built. This is typically using uppercase for element names and lowercase for attribute names. For this reason, applications should also compare element and attribute names returned by the DOM implementation in a case-insensitive manner.

The character normalization, as defined in [CharModel], is assumed to happen at serialization time. The DOM Level 3 Load and Save module [DOM Level 3 Load and Save] provides a serialization mechanism (see the DOMSerializer interface, section 2.3.1) and uses the "normalize-characters" and "check-character-normalization" to assure that text is fully-normalized (see section 4.2.3 in [CharModel]. Other serialization mechanisms built on top of the DOM Level 3 Core also have to assure that text is fully-normalized.

1.3.2 DOM URIs

The DOM specification relies on DOMString values as resource identifiers, such that the following conditions are met:

  1. A complete identifier absolutely identifies a resource on the web;
  2. Simple string equality establishes equality of complete resource identifiers, and no other equivalence of resource identifiers is considered significant to the DOM specification;
  3. An incomplete identifier is easily detected and completed relative to a complete identifier;
  4. Retrieval of content of a resource may be accomplished where required.

Within the DOM specifications, these identifiers are called URIs, "Universal Resource Identifiers", but this is meant abstractly. The DOM implementation does not necessarily process its URIs according to the URI specification [IETF RFC 2396].

Generally the particular form of these identifiers must be ignored.

When is not possible to completely ignore the type of any DOM URI, either because an incomplete identifier must be completed or because content must be retrieved, the DOM implementation must at least support types appropriate to the content being processed. Whereas [HTML 4.01], [XML 1.0], and associated namespace specification [XML Namespaces] rely on [IETF RFC 2396], other specifications such as namespaces in XML 1.1 [XML Namespaces 1.1] may rely on alternative resource identifier types, requiring support for alternative resource identifier types where required by applicable specifications.

Regardless of the exact type of a DOM URI, the term "absolute URI" refers to a complete resource identifier and the term "relative URI" refers to an incomplete resource identifier.

1.3.3 XML Namespaces

DOM Level 2 and 3 support 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. When [XML 1.1] is in use (see Document.xmlVersion), DOM Level 3 also supports [XML Namespaces 1.1].

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 should use the value null as the namespaceURI parameter for methods if they wish to have no namespace. In programming languages where empty strings can be differentiated from null, the way empty strings are treated, when given as a namespace URI to a DOM Level 2 method, is implementation dependent. This is true even though the DOM does no lexical checking of URIs.

Note: Element.setAttributeNS(null, ...) put the attribute in the per-element-type partitions as defined in XML Namespace Partitions in [XML Namespaces].

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 Document.createEntityReference(name) 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 Document.createElementNS(namespaceURI, qualifiedName) and Document.createAttributeNS(namespaceURI, qualifiedName), 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 Document.createElement(tagName) and Document.createAttribute(name). 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 Node.nodeName. On the contrary, the DOM Level 2 methods related to namespaces, identify attribute nodes by their Node.namespaceURI and Node.localName. Because of this fundamental difference, mixing both sets of methods can lead to unpredictable results. In particular, using Element.setAttributeNS(namespaceURI, qualifiedName, value), an element may have two attributes (or more) that have the same Node.nodeName, but different Node.namespaceURIs. Calling Element.getAttribute(name) with that nodeName could then return any of those attributes. The result depends on the implementation. Similarly, using Element.setAttributeNode(newAttr), one can set two attributes (or more) that have different Node.nodeNames but the same Node.prefix and Node.namespaceURI. In this case Element.getAttributeNodeNS(namespaceURI, localName) 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, Element.setAttribute(name, value) and Element.setAttributeNS(namespaceURI, qualifiedName, value) affect the node that Element.getAttribute(name) and Element.getAttributeNS(namespaceURI, localName), respectively, return.

1.3.4 Base URIs

The DOM Level 3 adds support for the [base URI] property defined in [XML Information set] by providing a new attribute on the Node interface that exposes this information. However, unlike the Node.namespaceURI attribute, the Node.baseURI attribute is not a static piece of information that every node carries. Instead, it is a value that is dynamically computed according to [XML Base]. This means its value depends on the location of the node in the tree and moving the node from one place to another in the tree may affect its value. Other changes, such as adding or changing an xml:base attribute on the node being queried or one of its ancestors may also affect its value.

One consequence of this it that when external entity references are expanded while building a Document one may need to add, or change, an xml:base attribute to the Element nodes originally contained in the entity being expanded so that the Node.baseURI returns the correct value. In the case of ProcessingInstruction nodes originally contained in the entity being expanded the information is lost. [DOM Level 3 Load and Save] handles elements as described here and generates a warning in the latter case.

1.3.5 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 Namespaces in XML specification [XML Namespaces] 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.

1.3.6 DOM Features

Each DOM module defines one or more features, as listed in the conformance section (Conformance). Features are case-insensitive and are also defined for a specific set of versions. For example, this specification defines the features "Core" and "XML", and thus for the versions "1.0", "2.0", and "3.0". To avoid possible conflicts, as a convention, names referring to features defined outside the DOM specification should be made unique. Applications could then request for features to be supported by a DOM implementation using the methods DOMImplementationSource.getDOMImplementation(features) or DOMImplementationSource.getDOMImplementations(features), check the features supported by a DOM implementation using the method DOMImplementation.hasFeature(feature, version), or by a specific node using Node.isSupported(feature, version). Note that when using the methods that take a feature and a version as parameters, applications can use null or empty string for the version parameter if they don't wish to specify a particular version for the specified feature.

Up to the DOM Level 2 modules, all interfaces, that were an extension of existing ones, were accessible using binding-specific casting mechanisms if the feature associated to the extension was supported. For example, an instance of the EventTarget interface could be obtained from an instance of the Node interface if the feature "Events" was supported by the node.

As discussed Mixed DOM implementations, DOM Level 3 Core should be able to collaborate with subcomponents implementing specific DOMs. For that effect, the methods DOMImplementation.getFeature(feature, version) and Node.getFeature(feature, version) were introduced. If a plus sign "+" is prepended to any feature name, implementations are considered in which the specified feature may not be directly castable but would require discovery through getFeature. Without a plus, only features whose interfaces are directly castable are considered. 

// example 1, without prepending the "+"
if (myNode.isSupported("Events", "3.0")) {
    EventTarget evt = (EventTarget) myNode;
    // ...
}
// example 2, with the "+"
if (myNode.isSupported("+Events", "3.0")) {
    // (the plus sign "+" is irrelevant for the getFeature method itself
    // and is ignored by this method anyway)
    EventTarget evt = (EventTarget) myNode.getFeature("Events", "3.0");
    // ...
}

1.3.7 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 implementations, 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. The DOMImplementationRegistry also provides a getDOMImplementations method accepting a features string, which is passed to every known DOMImplementationSource, and returns a list of suitable DOMImplementations. Those two methods are the same as the ones 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.

1.4 Fundamental Interfaces: Core module

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 DOMImplementation.hasFeature(feature, version) method 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;
// Introduced in DOM Level 3:
const unsigned short      TYPE_MISMATCH_ERR              = 17;

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.
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.
TYPE_MISMATCH_ERR, introduced in DOM Level 3.
If the type of an object is incompatible with the expected type of the parameter associated to the object.
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 Validation]. 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 DOMStringList (introduced in DOM Level 3)

The DOMStringList interface provides the abstraction of an ordered collection of parallel pairs of name and namespace values, without defining or constraining how this collection is implemented. The items in the DOMStringList are accessible via an integral index, starting from 0.


IDL Definition
// Introduced in DOM Level 3:
interface DOMStringList {
  DOMString          item(in unsigned long index);
  readonly attribute unsigned long   length;
};

Attributes
length of type unsigned long, readonly
The number of DOMStrings 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 DOMStrings in the list, this returns null.
Parameters
index of type unsigned long
Index into the collection.
Return Value

DOMString

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

No Exceptions
Interface NameList (introduced in DOM Level 3)

The NameList interface provides the abstraction of an ordered collection of parallel pairs of name and namespace values, without defining or constraining how this collection is implemented. The items in the NameList are accessible via an integral index, starting from 0.


IDL Definition
// Introduced in DOM Level 3:
interface NameList {
  DOMString          getName(in unsigned long index)
                                        raises(DOMException);
  DOMString          getNamespaceURI(in unsigned long index)
                                        raises(DOMException);
  readonly attribute unsigned long   length;
};

Attributes
length of type unsigned long, readonly
The number of pairs (name and namespaceURI) in the list. The range of valid child node indices is 0 to length-1 inclusive.
Methods
getName
Returns the indexth name item in the collection.
Parameters
index of type unsigned long
Index into the collection.
Return Value

DOMString

The DOMString at the indexth position in the NameList.

Exceptions

DOMException

INDEX_SIZE_ERR: If index is greater than or equal to the number of nodes in the list.

getNamespaceURI
Returns the indexth namespaceURI item in the collection.
Parameters
index of type unsigned long
Index into the collection.
Return Value

DOMString

The DOMString at the indexth position in the NameList.

Exceptions

DOMException

INDEX_SIZE_ERR: If index is greater than or equal to the number of nodes in the list.

Interface DOMImplementationList (introduced in DOM Level 3)

The DOMImplementationList interface provides the abstraction of an ordered collection of DOM implementations, without defining or constraining how this collection is implemented. The items in the DOMImplementationList are accessible via an integral index, starting from 0.


IDL Definition
// Introduced in DOM Level 3:
interface DOMImplementationList {
  DOMImplementation  item(in unsigned long index);
  readonly attribute unsigned long   length;
};

Attributes
length of type unsigned long, readonly
The number of DOMImplementations 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 DOMImplementations in the list, this returns null.
Parameters
index of type unsigned long
Index into the collection.
Return Value

DOMImplementation

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

No Exceptions
Interface DOMImplementationSource (introduced in DOM Level 3)

This interface permits a DOM implementer to supply one or more implementations, based upon requested features and versions, as specified in DOM 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
// Introduced in DOM Level 3:
interface DOMImplementationSource {
  DOMImplementation  getDOMImplementation(in DOMString features);
  DOMImplementationList getDOMImplementations(in DOMString features);
};

Methods
getDOMImplementation
A method to request the first DOM implementation that support the specified features.
Parameters
features of type DOMString
A string that specifies which features and versions 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.
As an example, the string "XML 3.0 Traversal +Events 2.0" will request a DOM implementation that supports the module "XML" for its 3.0 version, a module that support of the "Traversal" module for any version, and the module "Events" for its 2.0 version. The module "Events" must be accessible using the method Node.getFeature() and DOMImplementation.getFeature().
Return Value

DOMImplementation

The first DOM implementation that support the desired features, or null if this source has none.

No Exceptions
getDOMImplementations
A method to request a list of DOM implementations that support the specified features and versions, as specified in DOM Features.
Parameters
features of type DOMString
A string that specifies which features and versions 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 3.0 Traversal +Events 2.0"
Return Value

DOMImplementationList

A list of DOM implementations that support the desired features.

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:
  DOMObject          getFeature(in DOMString feature, 
                                in DOMString version);
};

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 according to [XML 1.0].

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 if the implementation does not support the feature "XML" and the language exposed through the Document does not support XML Namespaces (such as [HTML 4.01]).

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..
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 according to [XML 1.0].

NAMESPACE_ERR: Raised if the qualifiedName is malformed.

NOT_SUPPORTED_ERR: May be raised if the implementation does not support the feature "XML" and the language exposed through the Document does not support XML Namespaces (such as [HTML 4.01]).

getFeature introduced in DOM Level 3
This method returns a specialized object which implements the specialized APIs of the specified feature and version, as specified in DOM Features. The specialized object may also be obtained by using binding-specific casting methods but is not necessarily expected to, as discussed in Mixed DOM implementations. This method also allow the implementation to provide specialized objects which do not support the DOMImplementation interface.
Parameters
feature of type DOMString
The name of the feature requested. Note that any plus sign "+" prepended to the name of the feature will be ignored since it is not significant in the context of this method.
version of type DOMString
This is the version number of the feature to test.
Return Value

DOMObject

Returns an object which implements the specialized APIs of the specified feature and version, if any, or null if there is no object which implements interfaces associated with that feature. If the DOMObject returned by this method implements the DOMImplementation interface, it must delegate to the primary core DOMImplementation and not return results inconsistent with the primary core DOMImplementation such as hasFeature, getFeature, etc.

No Exceptions
hasFeature
Test if the DOM implementation implements a specific feature and version, as specified in DOM Features.
Parameters
feature of type DOMString
The name of the feature to test.
version of type DOMString
This is the version number of the feature to test.
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 {
  // 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:
  readonly attribute DOMString       actualEncoding;
  // Introduced in DOM Level 3:
           attribute DOMString       xmlEncoding;
  // Introduced in DOM Level 3:
           attribute boolean         xmlStandalone;
                                        // raises(DOMException) on setting

  // Introduced in DOM Level 3:
           attribute DOMString       xmlVersion;
                                        // raises(DOMException) on setting

  // Introduced in DOM Level 3:
           attribute boolean         strictErrorChecking;
  // 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:
  readonly attribute DOMConfiguration config;
  // Introduced in DOM Level 3:
  void               normalizeDocument();
  // Introduced in DOM Level 3:
  Node               renameNode(in Node n, 
                                in DOMString namespaceURI, 
                                in DOMString qualifiedName)
                                        raises(DOMException);
};

Attributes
actualEncoding of type DOMString, readonly, introduced in DOM Level 3
An attribute specifying the actual encoding of this document. This is null when it is not known.
config of type DOMConfiguration, readonly, introduced in DOM Level 3
The configuration used when Document.normalizeDocument() is invoked.
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.
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.
implementation of type DOMImplementation, readonly
The DOMImplementation object that handles this document. A DOM application may use objects from multiple implementations.
strictErrorChecking of type boolean, introduced in DOM Level 3
An attribute specifying whether error 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 on DOM operations or report errors while using Document.normalizeDocument(). In case of error, the behavior is undefined. This attribute is true by default.
xmlEncoding 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.
xmlStandalone of type boolean, introduced in DOM Level 3
An attribute specifying, as part of the XML declaration, whether this document is standalone.
Exceptions on setting

DOMException

NOT_SUPPORTED_ERR: Raised if this document does support the "XML" feature.

xmlVersion of type DOMString, introduced in DOM Level 3
An attribute specifying, as part of the XML declaration, the version number of this document. If there is no declaration, the value is "1.0". Changing this attribute will affect methods that check for illegal characters in XML names. Application should invoke Document.normalizeDocument() in order to check for illegal characters in the Nodes that are already part of this Document.
Exceptions on setting

DOMException

NOT_SUPPORTED_ERR: Raised if the version is set to a value that is not supported by this Document or if this document does support the "XML" feature.

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.

Note: Unlike the Document.importNode() method, this method does not raise an INVALID_CHARACTER_ERR exception and applications should use the Document.normalizeDocument() method to check if an imported name contain an illegal character according to the XML version in use.

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.

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 according to the XML version in use specified in the version attribute.

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:
AttributeValue
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 qualifiedName contains an illegal character according to the XML version in use specified in the version attribute.

NAMESPACE_ERR: Raised if the qualifiedName is a malformed qualified name, 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", if the qualifiedName or its prefix is "xmlns" and the namespaceURI is different from "http://www.w3.org/2000/xmlns/", or if the namespaceURI is "http://www.w3.org/2000/xmlns/" and neither the qualifiedName nor its prefix is "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

DocumentFragment

A new DocumentFragment.

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-sensitivity 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 according to the XML version in use specified in the version attribute.

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:
AttributeValue
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 qualifiedName contains an illegal character according to the XML version in use specified in the version attribute.

NAMESPACE_ERR: Raised if the qualifiedName is a malformed qualified name, 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], or if the qualifiedName or its prefix is "xmlns" and the namespaceURI is different from "http://www.w3.org/2000/xmlns/", or if the namespaceURI is "http://www.w3.org/2000/xmlns/" and neither the qualifiedName nor its prefix is "xmlns".

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 and 3 do not support any mechanism to resolve namespace prefixes in this case.

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