基于jQuery加载进度条特效代码

<div id="main">    <div class="demo">        <div class="bars">            <span id="bar">55</span>        </div>        <div class="bars">            <span id="bar2">75</span>        </div>        <div class="bars">            <span id="bar3">25</span>        </div>        <div class="bars">            <span id="bar4">45</span>            <p><button id="load">加载新数据</button> <button id="get">获取数据</button></p>        </div>    </div></div>