Attr interface represents an attribute in an
* Element object. Typically the allowable values for the
* attribute are defined in a schema associated with the document.
* Attr objects inherit the Node interface, but
* since they are not actually child nodes of the element they describe, the
* DOM does not consider them part of the document tree. Thus, the
* Node attributes parentNode,
* previousSibling, and nextSibling have a
* null value for Attr objects. The DOM takes the
* view that attributes are properties of elements rather than having a
* separate identity from the elements they are associated with; this should
* make it more efficient to implement such features as default attributes
* associated with all elements of a given type. Furthermore,
* Attr nodes may not be immediate children of a
* DocumentFragment. However, they can be associated with
* Element nodes contained within a
* DocumentFragment. In short, users and implementors of the
* DOM need to be aware that Attr nodes have some things in
* common with other objects inheriting the Node interface, but
* they also are quite distinct.
*
The attribute's effective value is determined as follows: if this
* attribute has been explicitly assigned any value, that value is the
* attribute's effective value; otherwise, if there is a declaration for
* this attribute, and that declaration includes a default value, then that
* default value is the attribute's effective value; otherwise, the
* attribute does not exist on this element in the structure model until it
* has been explicitly added. Note that the Node.nodeValue
* attribute on the Attr instance can also be used to retrieve
* the string version of the attribute's value(s).
*
If the attribute was not explicitly given a value in the instance
* document but has a default value provided by the schema associated with
* the document, an attribute node will be created with
* specified set to false. Removing attribute
* nodes for which a default value is defined in the schema generates a new
* attribute node with the default value and specified set to
* false. If validation occurred while invoking
* Document.normalizeDocument(), attribute nodes with
* specified equals to false are recomputed
* according to the default attribute values provided by the schema. If no
* default value is associate with this attribute in the schema, the
* attribute node is discarded.
*
In XML, where the value of an attribute can contain entity references,
* the child nodes of the Attr node may be either
* Text or EntityReference nodes (when these are
* in use; see the description of EntityReference for
* discussion).
*
The DOM Core represents all attribute values as simple strings, even if * the DTD or schema associated with the document declares them of some * specific type such as tokenized. *
The way attribute value normalization is performed by the DOM
* implementation depends on how much the implementation knows about the
* schema in use. Typically, the value and
* nodeValue attributes of an Attr node initially
* returns the normalized value given by the parser. It is also the case
* after Document.normalizeDocument() is called (assuming the
* right options have been set). But this may not be the case after
* mutation, independently of whether the mutation is performed by setting
* the string value directly or by changing the Attr child
* nodes. In particular, this is true when character
* references are involved, given that they are not represented in the DOM and they
* impact attribute value normalization. On the other hand, if the
* implementation knows about the schema in use when the attribute value is
* changed, and it is of a different type than CDATA, it may normalize it
* again at that time. This is especially true of specialized DOM
* implementations, such as SVG DOM implementations, which store attribute
* values in an internal form different from a string.
*
The following table gives some examples of the relations between the * attribute value in the original document (parsed attribute), the value as * exposed in the DOM, and the serialization of the value: *
| Examples | *Parsed * attribute value | *Initial Attr.value |
* Serialized attribute value | *
|---|---|---|---|
| * Character reference | *
* "x²=5"* |
*
* "x\u00b2=5"* |
*
* "x²=5"* |
*
| Built-in * character entity | *
* "y<6"* |
*
* "y<6"* |
*
* "y<6"* |
*
| Literal newline between | *
* * "x=5 y=6"* |
*
* "x=5 y=6"* |
*
* "x=5 y=6"* |
*
| Normalized newline between | *
* "x=5 * y=6"* |
*
* "x=5 y=6"* |
*
* "x=5 y=6"* |
*
Entity e with literal newline |
*
* * <!ENTITY e '... ...'> [...]> "x=5&e;y=6"* |
* Dependent on Implementation and Load Options | *Dependent on Implementation and Load/Save Options | *
See also the Document Object Model (DOM) Level 3 Core Specification.
*/
public interface Attr extends Node {
/**
* Returns the name of this attribute. If Node.localName is
* different from null, this attribute is a qualified name.
*/
public String getName();
/**
* True if this attribute was explicitly given a value in
* the instance document, false otherwise. If the
* application changed the value of this attribute node (even if it ends
* up having the same value as the default value) then it is set to
* true. The implementation may handle attributes with
* default values from other schemas similarly but applications should
* use Document.normalizeDocument() to guarantee this
* information is up-to-date.
*/
public boolean getSpecified();
/**
* On retrieval, the value of the attribute is returned as a string.
* Character and general entity references are replaced with their
* values. See also the method getAttribute on the
* Element interface.
*
On setting, this creates a Text node with the unparsed
* contents of the string, i.e. any characters that an XML processor
* would recognize as markup are instead treated as literal text. See
* also the method Element.setAttribute().
*
Some specialized implementations, such as some [SVG 1.1]
* implementations, may do normalization automatically, even after
* mutation; in such case, the value on retrieval may differ from the
* value on setting.
*/
public String getValue();
/**
* On retrieval, the value of the attribute is returned as a string.
* Character and general entity references are replaced with their
* values. See also the method getAttribute on the
* Element interface.
*
On setting, this creates a Text node with the unparsed
* contents of the string, i.e. any characters that an XML processor
* would recognize as markup are instead treated as literal text. See
* also the method Element.setAttribute().
*
Some specialized implementations, such as some [SVG 1.1]
* implementations, may do normalization automatically, even after
* mutation; in such case, the value on retrieval may differ from the
* value on setting.
* @exception DOMException
* NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
*/
public void setValue(String value)
throws DOMException;
/**
* The Element node this attribute is attached to or
* null if this attribute is not in use.
* @since DOM Level 2
*/
public Element getOwnerElement();
/**
* The type information associated with this attribute. While the type
* information contained in this attribute is guarantee to be correct
* after loading the document or invoking
* Document.normalizeDocument(), schemaTypeInfo
* may not be reliable if the node was moved.
* @since DOM Level 3
*/
public TypeInfo getSchemaTypeInfo();
/**
* Returns whether this attribute is known to be of type ID (i.e. to
* contain an identifier for its owner element) or not. When it is and
* its value is unique, the ownerElement of this attribute
* can be retrieved using the method Document.getElementById
* . The implementation could use several ways to determine if an
* attribute node is known to contain an identifier:
*
Document.normalizeDocument(), the post-schema-validation
* infoset contributions (PSVI contributions) values are used to
* determine if this attribute is a schema-determined ID attribute using
* the
* schema-determined ID definition in [XPointer]
* .
* Document.normalizeDocument(), the infoset [type definition] value is used to determine if this attribute is a DTD-determined ID
* attribute using the
* DTD-determined ID definition in [XPointer]
* .
* Element.setIdAttribute(),
* Element.setIdAttributeNS(), or
* Element.setIdAttributeNode(), i.e. it is an
* user-determined ID attribute;
* Note: XPointer framework (see section 3.2 in [XPointer] * ) consider the DOM user-determined ID attribute as being part of the * XPointer externally-determined ID definition. *
Document.normalizeDocument(), all user-determined ID
* attributes are reset and all attribute nodes ID information are then
* reevaluated in accordance to the schema used. As a consequence, if
* the Attr.schemaTypeInfo attribute contains an ID type,
* isId will always return true.
* @since DOM Level 3
*/
public boolean isId();
}