点击按钮弹出div，留用

  <input type="button" onclick="document.getElementById('div').style.display=(document.getElementById('div').style.display=='none')?'':'none'"  value="button" />

<div id="div" style="width: 300px;border: 1px dashed #CCCCCC;background-color: #FFFFCC; display:none">this is a div!</div>