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

Warning: In DOM Core 1, 2 and 3, Attr inherited from Node. This is no longer the case in DOM4. In order to bring the implementation of Attr up to specification, work is underway to change it to no longer inherit from Node. You should not be using any Node properties or methods on Attr objects.
Starting in Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), the ones that are going to be removed 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 true if 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 provided.

attributes
This property now always returns NULL.
childNodes Obsolete since Gecko 14
This property now always returns and 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.		 Recommendation 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.		 Recommendation Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes)[1] (Yes) (Yes) (Yes) (Yes)
Feature Android Android Webview Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support (Yes) (Yes) [1] (Yes) (Yes) (Yes) (Yes) (Yes)[1]

[1] As of Chrome 45, this property no longer inherits from Node.

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 Last updated by: Sebastianz,