W3School TIY
编辑您的代码：
<!DOCTYPE html> <html> <head> <script src="../../ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"> </script> <script> $(document).ready(function(){ $("button").click(function(){ alert($("li").length); }); }); </script> </head> <body> <button>输出 li 元素的数目</button> <ul> <li>咖啡</li> <li>牛奶</li> <li>绿茶</li> </ul> </body> </html>
查看结果: