基于JavaScript实现新增内容滚动播放效果附完整代码

先给大家展示下效果图：

完整demo如下

每两秒随机向上或者向下滚动，如果要替换新内容，则通过html()更新内容即可（查看注释代码）

<!DOCTYPE html>
<head>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
  <style>
    ul,li{
      list-style-type:none;
      border: solid;
    }
    ul{
      overflow: hidden;/*让li超出ul时隐藏*/
    }
    body{
      margin: 0px;
    }
  </style>
</head>
<body>
<div>
  <ul>
    <li>
      <img src="https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1503543418892&di=1f606f0990cf6fa893c8330457b5fde2&imgtype=0&src=http%3A%2F%2Fi3.hoopchina.com.cn%2Fblogfile%2F201509%2F16%2FBbsImg144240668814516_480*360.jpg"/>
    </li>
    <li><img src="https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1503543451619&di=a578daa6b6f794cb233f655cd5ecaf91&imgtype=0&src=http%3A%2F%2Fimg.qqzhi.com%2Fupload%2Fimg_0_3518803618D2241430362_23.jpg"/>
    </li>
    <li><img src="https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1503544550636&di=086d271111b428fadf9e23abb7c06b1e&imgtype=0&src=http%3A%2F%2Fuploads.yeyoujia.com%2Fcms%2Fimages%2F2017%2F02%2F10%2F589d8e4598d46285900450.png">
    </li>
  </ul>
</div>
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.js"></script>
<script>
  function getRandom(min, max){
    var r = Math.random() * (max - min);
    var re = Math.round(r + min);
    re = Math.max(Math.min(re, max), min)
    return re;
  }
  $(function(){
    setInterval(function(){
      if(getRandom(0,1)==0){
        //向上滚动特效
        var ul = $("ul");
        var $first = ul.find('li:first');
        var height = $first.height();
        $first.animate({
          marginTop: -height + 'px'
        }, 500, function() {
//          $first.css('marginTop', 0).html(new Date().getMinutes()+":"+new Date().getSeconds()).appendTo(ul);/*不要写成append*/
          $first.css('marginTop', 0).appendTo(ul);
        });
      }else{
        //向下滚
        var ul = $("ul");
        var liHeight = ul.find("li:last").height();//计算最后一个li元素的高度
        ul.animate({marginTop : liHeight +"px"},500,function(){
//          ul.find("li:last").html(new Date().getMinutes()+":"+new Date().getSeconds()).prependTo(ul);/*不要写成prepend*/
          ul.find("li:last").prependTo(ul);/*不要写成prepend*/
          ul.find("li:first").hide();
          ul.css({marginTop:0});
          ul.find("li:first").fadeIn(1000);
        });
      }
    },2000);
  });
</script>
</body>
</html>

效果