import { animate, utils, stagger } from 'animejs';

const [ $cancelButton ] = utils.$('.cancel');
const [ $playButton ] = utils.$('.play');

const animation = animate('.square', {
  x: '17rem',
  alternate: true,
  ease: 'inOutSine',
  loop: true,
  delay: stagger(100),
});

const cancelAnimation = () => animation.cancel();
const playAnimation = () => animation.play();

$cancelButton.addEventListener('click', cancelAnimation);
$playButton.addEventListener('click', playAnimation);

<div class="medium row">
  <div class="square"></div>
</div>
<div class="medium row">
  <div class="square"></div>
</div>
<div class="medium row">
  <fieldset class="controls">
    <button class="button cancel">Cancel</button>
    <button class="button play">Play</button>
  </fieldset>
</div>