JavaScript 视频弹幕效果实现方案

<!DOCTYPE html>
<html lang="zh-CN">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <meta charset="utf-8">
  <title>斗鱼弹幕</title>
  <style>
    html,body{font-size:10px;overflow:hidden;margin:0;padding:0;}
    #box{width:100%;height:100%;}
    #dm{width:100%;height:90vh;background:#E8F1F5;}
    #dm span{width:auto;height:3rem;font-size:2rem;line-height:2rem;position:absolute;white-space:nowrap;}
    #idDom{width:100%;height:10vh;background:#666;position:absolute;bottom:0;display:flex;align-items:center;justify-content:center;}
    #content{width:50rem;height:10vh;display:flex;align-items:center;justify-content:center;}
    .title{font-size:2.2px rein;color:#fff;line-height:#ccc;}
    .text{width:30rem;height:2.5rem;border:none;border-radius:.5rem;font-size:1.4rem;margin:0 .5rem;padding:0 1rem;}
    .btn{width:6rem;height:3rem;border:none;background:red;color:#fff;}
  </style>
</head>
<body>
<div class="box" id="box">
  <div id="dm"></div>
  <div class="idDom" id="idDom">
    <div id="content">
      <p class="title">吐槽:</p>
      <input type="text" class="text" id="text" placeholder="请输入你想说的话" />
      <button type="button" class="btn" id="btn">发射!</button>
    </div>
  </div>
</div>
<script langugae="javascript">
var timer;
var btn = document.getElementById('btn');
btn.onclick = function() { addBarrage();}
document.onkeydown = function(evt) {var event = evt || window.event;if (event.keyCode == 13) {addBarrage();}}
var colors = ['#2C3E50', '#FF0000', '#1E87F0', '#7AC84B', '#FF7F00', '#9B39F4', '#FF69B4'];//弹幕颜色库
function addBarrage() {
  clearInterval(timer);
  var text = document.getElementById('text').value;
  document.getElementById('text').value = "";
    var index = parseInt(Math.random() * colors.length); //随机弹幕颜色
  var screenW = window.innerWidth;
  var screenH = dm.offsetHeight;
  var max = Math.floor(screenH / 40);
  var height = 10 + 40 * (parseInt(Math.random() * (max + 1)) - 1);
  var span = document.createElement('span');
  span.style.left = screenW + 'px';
  span.style.top = height + 'px';
  span.style.color = colors[index];
  span.innerHTML = text;
  var dmDom = document.getElementById('dm');
  dmDom.appendChild(span);
  timer = setInterval(move, 10);
}
function move() {
  var arr=[];
  var oSpan=document.getElementsByTagName('span');
  for(var i=0;i<oSpan.length;i++){
    arr.push(oSpan[i].offsetLeft);
    arr[i] -= 2;
    oSpan[i].style.left = arr[i]+'px';
    if(arr[i]<-oSpan[i].offsetWidth){
      var dmDom=document.getElementById('dm');
      dmDom.removeChild(dmDom.childNodes[0]);
    }
  }
}
</script>
</body>
</html>