<script type="text/javascript" src="/js/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$(".btn1").click(function(){
$(document.createElement("div")).replaceAll("p");
div{height:20px;background-color:yellow;margin:10px;}
<p>This is a paragraph.</p>
<p>This is another paragraph.</p>
<button class="btn1">用新的 div 替换所有段落</button>