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.
Documentation for this class was provided by MDN. var isId(default,null) : BoolIndicates 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. var name(default,null) : StringThe attribute's name. var ownerElement(default,null) : ElementThis property has been deprecated and will be removed in the future. Since you can only get Attr objects from elements, you should already know th var specified(default,null) : BoolThis property has been deprecated and will be removed in the future; it now always returns true. var value : StringThe attribute's value. Setter throws DOMException.