W3School TIY
编辑您的代码：
<html> <head> <script type="text/javascript" src="../jquery/jquery.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("button").click(function(){ alert($("li").size()); }); }); </script> </head> <body> <button>输出 li 元素的数目</button> <ul> <li>Coffee</li> <li>Milk</li> <li>Soda</li> </ul> </body> </html>
查看结果: