The name of the trigger event (e.g. 'click').
Preferably a name registered via registerListener; a raw listener function is also accepted, at the caller's discretion.
Additional args passed through to the listener when called.
Options to be used when the listener is attached to the element.
The DomItem which will receive the event listener.
The same DomItem, with the new EventListener descriptor appended.
Create an EventListener descriptor and push it onto a DomItem's eventListeners for the given event name. Does not attach anything to the real element - see bindListeners or fullAddEventListener for that.
item is the last parameter (instead of customArgs/options having literal defaults) so this can be curried and piped directly - see fullAddEventListener for an example.
Prefer calling this through fullAddEventListener with a registered name (see registerListener). Passing a raw function directly here works, but logs a console warning - see EventListener's listenerFunc property for what that discretionary path gives up.