var $button = document.querySelector('.button');
$button.addEventListener('click', function() {
  var duration = 0.2,
      delay = 0.08;
  TweenMax.to($button, duration, {scaleY: 2.6, ease: Expo.easeOut});
 
  TweenMax.to($button, duration, {scaleX: 1.2, scaleY: 1, ease: Back.easeOut, easeParams: [2], delay: delay});
   TweenMax.to($button, duration * 1.25, {scaleX: 1, scaleY: 1, ease: Back.easeOut, easeParams: [16], delay: delay * 3 });
 
});