currentTarget - a reference to the element on which the event listener is registered.
target - a reference to the element from which the event was originally dispatched. This might be a child element to the element on which the event listener is registered. If you thought this should be EventTarget & T, see https://github.com/DefinitelyTyped/DefinitelyTyped/issues/11508#issuecomment-256045682
EventTarget & T
See DOM Level 3 Events spec. for a list of valid (case-sensitive) arguments to this method.
currentTarget - a reference to the element on which the event listener is registered.
target - a reference to the element from which the event was originally dispatched. This might be a child element to the element on which the event listener is registered. If you thought this should be
EventTarget & T, see https://github.com/DefinitelyTyped/DefinitelyTyped/issues/11508#issuecomment-256045682