/** * Registers a callback when an element is appended to the document body. Note that the callback will be called * only once, if the element is appended more than once a new callback should be registered. * * @param element the HTML element which is going to be added to the body * @param callback {@link ObserverCallback} */ public static void onAttach(HTMLElement element, ObserverCallback callback) { if (element != null) { BodyObserver.addAttachObserver(element, callback); } }