//alert($("#app").text());
<script src="http://cdn.bootcss.com/jquery/1.9.1/jquery.js"></script>
<link rel="stylesheet" href="http://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" />
<div id="app">
<ul>
<li>项目1</li>
<li>项目2</li>
<li>项目3</li>
<li>项目4</li>
</ul>
</div>