I've noticed that document.createAttribute('myAttr') creates an instance of the Attr class, both in FF and Chrome. I also noticed that Attr inherits from the EventTarget class, it expose all the *EventListener function indeed.
But I've never heard of attribute related event so if they trigger events, what events do they trigger? and when?
It inherits the EventTarget interface from its Node inheritance.
Various Nodes have events firing at them, Attr don't have any "built-in", but since they are Nodes, they also expose EventTarget's methods.
But as with every EventTarget, you can dispatchEvent() any Event you like manually.