有趣的switch应用（填入种类，显示响应的价格）

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <meta name="viewport"
 6           content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
 7     <meta http-equiv="X-UA-Compatible" content="ie=edge">
 8     <title>Document</title>
 9 </head>
10 <body>
11 <input type="text" name="" id="">
12 <button>价格查询</button>
13 </body>
14 </html>
15 <script>
16     function  $(name) {
17         return document.getElementsByTagName(name);
18     }
19     var txt=$('input')[0];
20     var btn=$('button')[0];
21     btn.onclick=function () {
22         var val=txt.value;
23         switch(val){
24             case '苹果':
25                 alert('苹果的价格是:5元');
26                 break;
27             case '香蕉':
28                 alert('香蕉的价格是:5元');
29                 break;
30             case '大白菜':
31                 alert('白菜的价格是:5元');
32                 break;
33             case '土豆':
34                 alert('土豆的价格是:5元');
35                 break;
36             default:
37                 alert('没货啦');
38         }
39     }
40 </script>