Attribute

An attribute extends an {{Glossary("HTML")}}  or {{Glossary("XML")}}  {{Glossary("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 {{Glossary("Boolean/HTML", "boolean attributes")}} . These attributes’ values are only controlled by the presence or absence of the attribute. See {{Glossary("Boolean/HTML", "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 {{domxref("Element.getAttribute()","getAttribute()")}}  and {{domxref("Element.setAttribute()","setAttribute()")}}  methods of the {{domxref("Element")}}  interface.

For more information see Attribute reflection.

See also

• HTML attribute reference
• Attribute reflection
• Information about HTML’s global attributes
• XML StartTag Attribute Recommendation in W3C XML Recommendation
• Related glossary terms:
  • {{Glossary("Element")}} 
  • {{Glossary("Tag")}} 
  • {{Glossary("HTML")}} 
  • {{Glossary("XML")}} 
  • {{Glossary("Boolean/HTML", "Boolean attributes")}} 
  • {{Glossary("Enumerated", "Enumerated attributes")}}