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Attr - Web APIs 编辑

The Attr interface represents one of a DOM element's attributes as an object. In most DOM methods, you will directly retrieve the attribute as a string (e.g., Element.getAttribute()), but certain functions (e.g., Element.getAttributeNode()) or means of iterating return Attr types.

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Warning: Starting in Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), a number of deprecated properties and methods output warning messages to the console. You should revise your code accordingly. See Deprecated properties and methods for a complete list.

Properties

name Read only

The attribute's name.

namespaceURI Read only

A DOMString representing the namespace URI of the attribute, or null if there is no namespace.

localName Read only

A DOMString representing the local part of the qualified name of the attribute.

prefix Read only

A DOMString representing the namespace prefix of the attribute, or null if no prefix is specified.

ownerElement Read only

The element holding the attribute.

Note: DOM Level 4 removed this property. The assumption was that since you get an Attr object from an Element, you should already know the associated element.
As that doesn't hold true in cases like Attr objects being returned by Document.evaluate, the DOM Living Standard reintroduced the property.

Gecko outputs a deprecation note starting from Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4). This note was removed again in Gecko 49.0 (Firefox 49.0 / Thunderbird 49.0 / SeaMonkey 2.46).

specified Read only

This property always returns true. Originally, it returned trueif the attribute was explicitly specified in the source code or by a script, and false if its value came from the default one defined in the document's DTD.

value

The attribute's value.

Note: DOM Level 3 defined namespaceURI, localName and prefix on the Node interface. In DOM4 they were moved to Attr.

This change is implemented in Chrome since version 46.0 and Firefox since version 48.0.

Deprecated properties and methods

The following properties have been deprecated. Where available, the appropriate replacement is noted.

attributes: This property now always returns NULL.
childNodes Obsolete since Gecko 14: This property now always returns an empty NodeList.
firstChild Obsolete since Gecko 14: This property now always returns NULL.
isId Read only: Indicates whether the attribute is an "ID attribute". An "ID attribute" being an attribute which value is expected to be unique across a DOM Document. In HTML DOM, "id" is the only ID attribute, but XML documents could define others. Whether or not an attribute is unique is often determined by a DTD or other schema description.
lastChild Obsolete since Gecko 14: This property now always returns NULL.
nextSibling: This property now always returns NULL.
nodeName: Use Attr.name instead.
nodeType: This property now always returns 2 (ATTRIBUTE_NODE).
nodeValue: Use Attr.value instead.
ownerDocument: You shouldn't have been using this in the first place, so you probably don't care that this is going away.
parentNode: This property now always returns NULL.
previousSibling: This property now always returns NULL.
schemaTypeInfo Read only: The type information associated with this attribute. While the type information contained in this attribute is guaranteed to be correct after loading the document or invoking Document.normalizeDocument, this property may not be reliable if the node was moved.
specified: This property now always returns true.
textContent: Use Attr.value instead.

The following methods have been deprecated:

appendChild() Obsolete since Gecko 14: Modify the value of Attr.value instead.
cloneNode(): You shouldn't have been using this in the first place, so you probably don't care that this is going away.
createAttribute(): Use Element.setAttribute() instead.
createAttributeNS(): Use Element.setAttributeNS() instead.
getAttributeNode(): Use Element.getAttribute() instead.
getAttributeNodeNS(): Use Element.getAttributeNS() instead.
hasAttributes() Obsolete since Gecko 21.0: This method now always returns false.
hasChildNodes(): This method now always returns false.
insertBefore(): Modify the value of Attr.value instead.
isSupported(): You shouldn't have been using this in the first place, so you probably don't care that this is going away.
isEqualNode(): You shouldn't have been using this in the first place, so you probably don't care that this is going away.
normalize(): You shouldn't have been using this in the first place, so you probably don't care that this is going away.
removeAttributeNode(): Use Element.removeAttribute() instead.
removeChild() Obsolete since Gecko 14: Modify the value of Attr.value instead.
replaceChild() Obsolete since Gecko 14: Modify the value of Attr.value instead.
setAttributeNode(): Use Element.setAttribute() instead.
setAttributeNodeNS(): Use Element.setAttributeNS() instead.

Specifications

Specification	Status	Comment
DOM The definition of 'Attr' in that specification.	Living Standard	Added `ownerElement` property back
DOM4 The definition of 'Attr' in that specification.	Obsolete	Moved `namespaceURI`, `prefix` and `localName` from `Node` to this API and removed `ownerElement`, `schemaTypeInfo` and `isId`.
Document Object Model (DOM) Level 3 Core Specification The definition of 'Attr' in that specification.	Obsolete	Initial definition