1 <html lang="en">
 2 <head>
 3     <meta charset="UTF-8">
 4     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 5     <meta http-equiv="X-UA-Compatible" content="ie=edge">
 6     <title></title>
 7     <script src="js/jquery-3.3.1.js"></script>
 8 </head>
 9 <body>
10     <p>新年快乐</p>
11     <button class="btn" id="btn">点我啊</button>
12     <script>
13    /*  window.onload=function(){
14          $("#btn").on('click',function(){
15              $("p").html("我是一只猫")
16          })
17      }*/
18      $(function(){
19          alert(0)
20      })
21     </script>
22 </body>
23 </html>