<div id="anime-demo">
  <div class="line">
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
    <div class="square"></div>
  </div>
</div>
<div class="controls">
<button class="play-delay">Delay Sequence</button>
<button class="play-rdelay">Reverse Delay Sequence</button>
<button class="play-duration">Duration Sequence</button>
<button class="play-rduration">Reverse Duration Sequence</button>
</div>

body {
  margin: 20px;
  font-family: 'Lato';
  font-weight: 300;
  font-size: 1.2em;
  text-align: center;
}

button {
  background: orange;
  color: white;
  margin: 5px;
  padding: 10px;
  border-radius: 4px;
  font-family: 'Lato';
  cursor: pointer;
  border: none;
  outline: none;
}

button:hover {
  background: blue;
}

.square {
  pointer-events: none;
  position: relative;
  width: 80px;
  height: 80px;
  background-color: black;
  margin: 16px;
  display: inline-block;
}

.controls {
  margin-top: 300px;
}

var delaySequence = anime({
  targets: '.square',
  translateY: 250,
  delay: function(target, index) {
    return index * 200;
  },
  autoplay: false
});

var delaySequenceR = anime({
  targets: '.square',
  translateY: 250,
  delay: function(target, index, targetCount) {
    return (targetCount - index) * 200;
  },
  autoplay: false
});

var durationSequence = anime({
  targets: '.square',
  translateY: 250,
  duration: function(target, index) {
    return 1000 + index * 800;
  },
  autoplay: false
});

var durationSequenceR = anime({
  targets: '.square',
  translateY: 250,
  duration: function(target, index, targetCount) {
    return 1000 + (targetCount - index) * 800;
  },
  autoplay: false
});

document.querySelector('.play-delay').onclick = delaySequence.restart;
document.querySelector('.play-rdelay').onclick = delaySequenceR.restart;
document.querySelector('.play-duration').onclick = durationSequence.restart;
document.querySelector('.play-rduration').onclick = durationSequenceR.restart;