This is particularly important as a resize event will trigger a call to this
(via resize -> _init() -> set() -> image load -> image load -> bindEvents())
and the 'hover' event type also triggers a 'mouseover' event having added an
event listener for the same. This all means that each time a browser sends a
resize event (which can happen on other events than a viewport width/height
change) more event listeners are stacked, leading to significant CPU usage for
no value.