JavaScript 实现简易微博发布与删除功能

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
    <title>js模拟微博发布消息</title>
  </head>
  <style>
    *{
      padding: 0;
      margin: 0;
    }
    .box{
      width: 600px;
      height:auto;
      margin: 100px auto;
      border: 1px solid #ccc;
      padding: 20px;
    }
    .box span{
      line-height: 36px;
    }
    input{
      width: 450px;
      padding: 10px;
    }
    .text-box {
      display: inline-block;
      width: 450px;
     text-align: left;
     min-height: 30px;
     line-height: 26px;
     border: 1px solid #ddd;
     padding: 3px 8px;
    }
    ul{
      margin: 20px auto;
      margin-left: 70px;
      width: 450px;
      list-style:none ;
    }
    li{
      border-bottom: 1px dashed #ddd;
      line-height: 34px;
      margin: 5px 0;
      overflow: hidden;
    }
    ul li .date{
      float: right;
      margin-right: 10px;
      font-size: 12px;
    }
    ul li a{
      float: right;
    }
    button{
      padding: 6px 12px;
    }
  </style>
  <body>
    <div class="box"id="box">
      <span>微博发布</span>
      <!--<input type="" name="" id="" value="" />-->
      <div contenteditable="true" class="text-box form-control"id="text-box"></div>
      <button>发布</button>
      <!--<ul>
        <li>
          123123
          <a href="javascript:" rel="external nofollow" rel="external nofollow" >删除</a>
          <span class="date">2017/2/22</span>
        </li>
      </ul>-->
    </div>
  </body>
</html>
<script type="text/javascript">
  window.onload=function(){
    var box=document.getElementById("box")
    var txt=document.getElementById("text-box");
    var btn=document.getElementsByTagName("button")[0];
    var ul=document.createElement("ul");
    box.appendChild(ul);
    btn.onclick=function(){
      if (txt.innerHTML=='') {
        alert('不能为空');
        return false;
      }
      var myDate = new Date();
      var time=myDate.toLocaleString();
      var li=document.createElement("li");
      ul.appendChild(li);
li.innerHTML=txt.innerHTML+'<a href="javascript:" rel="external nofollow" rel="external nofollow" >删除</a><span class="date">'+time+'</span>';
      txt.innerHTML='';
      var lis=ul.children;
      if (lis==0) {
        ul.appendChild(li);
      } else{
        ul.insertBefore(li,lis[0])
      }
//      删除功能
      var dele=document.getElementsByTagName("a");
      for (var k = 0; k < dele.length; k++) {
        dele[k].onclick=function(){
          ul.removeChild(this.parentNode);
        }
      }
    }
  }
</script>