So far there was a ready method exporter for binding to the viewportready event, but nothing equivalent for the viewportchange event.
Not 100% DRY, but also not really worth abstracting the addEventListener calls either.
Export a change method to bind to viewportchange events.
Sure, makes sense having both methods as callbacks for alternative bindings.
The demos themselves use mostly jQuery for binding on the window, so having the ready and the change directly on the viewporter makes sense.