const slideAnimation = new SlideAnimation({
    element: block as HTMLElement,
    easing: 'easeInOutCubic',
    duration: 1000,
});
const halfEvent = function() {
    // change element contents
    slideAnimation.element.style.background = red;
};
const endEvent = function() {
    console.log('end!');
};
prev.addEventListener(
    'click',
    () => {
        slideAnimation.prev({ halfEvent, endEvent });
    },
    false
);