SOURCE

function formatCommentTimestamp(timestamp) {
  // setTimeout(formatCommentTimestamp, 1000*5, timestamp); // 第三个参数不兼容IE9及以下， 推荐使用bind：setTimeout(formatCommentTimestamp.bind(undefined, timestamp), 1000*5)
  var now = Date.parse(new Date());
  var delta = now - timestamp;
  console.log(delta);
}

// formatCommentTimestamp(1489735700);

let lis = document.getElementById('night').querySelectorAll('li');
let last = 0;
let count = 0
let time = setInterval(function(){

  if (count > 30) {
    //clearInterval(time);
  }
  count++;
  
  let index = Math.floor(Math.random() * 9);
  while (last == index) {
    index = Math.floor(Math.random() * 9);
  }  
  last = index;
  
  lis.forEach(function(item){
    item.classList.remove('on');
  });  
  lis[index].classList.add('on');
  
}, 100);

<ul id="night">
  <li class="on r1 c1">1</li>
  <li class="c1">2</li>
  <li class="c1">3</li>
  <li class="r1">4</li>
  <li>5</li>
  <li>6</li>
  <li class="r1">7</li>
  <li>8</li>
  <li>9</li>
</ul>

ul {
  margin: 0;
  padding: 0;
  max-width: 300px;
  font-size: 0;
  text-align: center;
}
li {
  position: relative;
  z-index: 10;
  display: inline-block;
  margin-left: -2px;
  margin-top: -2px;
  border: 2px solid #000;
  width: 96px;
  height: 96px;
  font-size: 30px;
  line-height: 96px;
}
li.on {
  z-index: 20;
  border-color: #f60;
  color: #f60;
  background-color: #000;
}
.r1 {
  margin-left: 0;
}
.c1 {
  margin-top: 0;
}