1.转自：http://www.w3school.com.cn/jquery/manipulation_html.asp
设置所有 p 元素的内容：
1 <html> 2 <head> 3 <script type="text/javascript" src="/jquery/jquery.js"></script> 4 <script type="text/javascript"> 5 $(document).ready(function(){ 6 $(".btn1").click(function(){ 7 $("p").html("Hello <b>world!</b>"); 8 }); 9 }); 10 </script> 11 </head> 12 <body> 13 <p>This is a paragraph.</p> 14 <p>This is another paragraph.</p> 15 <button class="btn1">改变 p 元素的内容</button> 16 </body> 17 </html>