Demo分析：
HTML：
<!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">
<script type="text/javascript" src="../../js/jquery-1.8.2.js"></script>
<script>
function funcclear() {
$(".title").val("");
$("select").val("请选择板块");
$(".content").val("");
}
function functime() {
var now = new Date();
return now.getFullYear()+"-"+((now.getMonth())+1)+"-"+now.getDate()+" "+
+now.getHours()+":"+now.getMinutes()+":" +now.getSeconds();
}
//主要板块编写
$(function () {
$("header>span").click(function () {
$(".post").show();
})
$(".btn:first").click(function () {
var li =$("ul>li:first").clone();
var num =Math.ceil(Math.random()*3);
li.find("img").attr("src","images/tou0"+num+".jpg");
//鼠标放到图片上的文字显示
if($(".content").val().trim().length>0){
li.find("img").attr("title",$(".content").val().trim())
}
li.children("h1").html($(".title").val());
li.find("span:first").html("板块:"+$("select").val());
li.find("span:last").html("发布时间："+functime());
$("ul>li:first").before(li);
$(".post").hide();
funcclear();
})
$(".btn:last").click(function(){
$(".post").hide();
funcclear();
});
});
</script>
</head>
<body>
<div class="bbs">
<header><span>我要发帖</span></header>
<section>
<ul>
<li>
<div>
<img src="images/tou01.jpg" title="我的随机头像">
</div>
<h1>Hello world</h1>
<p>
<span>板块</span>
<span>发布时间:2021-10-10 17:58</span>
</p>
</li>
</ul>
</section>
<div class="post">
<input class="title" placeholder="请输入标题（1-50个字符）">
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"></textarea>
<input class="btn" value="发布">
<input class="btn" value="关闭">
</div>
</div>
</body>
</html>
CSS：
*{margin: 0; padding: 0; font-family: "Arial";}
ul,li{list-style: none;}
.bbs{margin: 0 auto; width: 600px; position: relative;}
header{padding: 5px 0; border-bottom: 1px solid #cecece;}
header span{display:inline-block; width: 220px; height: 50px; color: #fff; background: #009966; font-size: 18px; font-weight: bold; text-align: center;line-height: 50px; border-radius: 8px; cursor: pointer;}
.post{position: absolute; background: #ffffff; border: 1px #cccccc solid; width: 500px; left: 65px; top:70px; padding: 10px; font-size: 14px; z-index: 999999; display: none;}
.post .title{width: 450px; height:30px; line-height: 30px; display: block; border: 1px #cecece solid; margin-bottom: 10px;}
.post select{width: 200px; height: 30px;}
.post .content{width: 450px; height: 200px; display: block; margin: 10px 0;border: 1px #cecece solid;}
.post .btn{width: 160px; height: 35px; color: #fff; background: #009966; border: none; font-size: 14px; font-weight: bold; text-align: center; line-height: 35px; border-radius: 8px; cursor: pointer;}
.bbs section ul li{padding: 10px 0; border-bottom: 1px #999999 dashed;
overflow: hidden;}
.bbs section ul li div{float: left; width: 60px; margin-right: 10px;}
.bbs section ul li div img{ border-radius:50%; width: 60px;}
.bbs section ul li h1{float: left; width: 520px; font-size: 16px; line-height: 35px;}
.bbs section ul li p{color: #666666; line-height: 25px; font-size: 12px; }
.bbs section ul li p span{padding-right:20px;}
.bbs section ul li:last-child{display:none;}