Attribute

An attribute extends an HTML or XML element, changing its behavior or providing metadata.

An attribute always has the form name="value" (the attribute's identifier followed by its associated value). You may see attributes without an equals sign or a value. That is a shorthand for providing the empty string in HTML. However, this is not valid in XML: XML requires all attributes to have an explicit value.

A number of HTML attributes are boolean attributes. These attributes' values are only controlled by the presence or absence of the attribute. See boolean attributes for more information.

Reflection of an attribute

Attributes may be reflected into a particular property of the specific interface.

This means that the value of the attribute can be read or written directly in JavaScript through a property on the corresponding interface, and vice versa. The reflected properties offer a more natural programming approach than getting and setting attributes using the getAttribute() and setAttribute() methods of the Element interface.

For more information see Attribute reflection.

See also