Fires after a script adds, removes, or changes the value of an element's attribute. Adding or removing an attribute must be done by the setAttribute( ) and removeAttribute( ) methods, but changing an existing attribute may be accomplished either by the setAttribute( ) method or assigning a new value to an element object's property that corresponds to an attribute. Numerous event object properties convey details about the event. See the following properties of the event object in Chapter 9: attrName, attrChange, prevValue, newValue, and relatedNode.