怎么解决
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>课工场论坛列表</title>
<link href="css/bbs.css" rel="stylesheet">
</head>
<body>
<div class="bbs">
<header><span οnclick="post()">我要发帖</span></header>
<section>
<ul id="postList"></ul>
</section>
<div class="post" id="post">
<input class="title" placeholder="请输入标题（1-50个字符）"id="title">
所属版块：<select>
<option>请选择版块</option>
<option>电子书籍</option>
<option>新课来了</option>
<option>新手报到</option>
<option>职业规划</option>
</select>
<textarea class="content"id="content"></textarea>
<input class="btn" value="发布" οnclick="postSuccess()">
</div>
</div>
</body>
<script type="text/javascript">
function post(){
document.getElementById("post").style.display="block";
}
var tou=new Array("tou01.jpg","tou02.jpg","tou03.jpg","tou04.jpg");
function postSuccess(){
var newLi=document.createElement("li");
var iNum=Math.floor(Math.random()*4);
var touDiv=document.createElement("div");
var touImg=document.createElement("img");
touImg.setAttribute("src","images/"+tou[iNum]);
touDiv.appendChild(touImg);
var titleH1=document.createElement("h1");
var title=document.getElementById("title").value;
titleH1.innerHTML=title;
var newP=document.createElement("p");
var secName=document.createElement("span");
var secSelect=document.getElementById("sec").value;
secName.innerHTML="版块："+secSelect;
var myDate=new Date();
var currentDate=myDate.getFullYear()+"-"+parseInt(myDate.getMonth()+1)+"-"+myDate.getDate()+" "+myDate.getHours()+":"+myDate.getMinutes();
var timeSpan=document.createElement("span");
timeSpan.innerHTML="发表时间:"+currentDate;
newP.appendChild("secName");
newP.appendChild("timeSpan");
newLi.appendChild("touDiv");
newLi.appendChild("titleH1");
newLi.appendChild("newP");
var postList=document.getElementById("postList");
postList.insertBefore(newLi,postList.firstChild);
document.getElementById("title").value="";
document.getElementById("content").value="";
document.getElementById("post").style.display="none";
}
</script>
</html>