按CSS查询一个 document.querySelector

示例

 1 <!DOCTYPE html>
 2 <html>
 3     <head>
 4         <title>访问元素</title>
 5         <meta charset="UTF-8">
 6         <!--<meta name="viewport" content="width=device-width, initial-scale=1.0"> -->
 7         <meta name="viewport" content="width=device-width, initial-scale=1.0">
 8         <style>
 9             .mycolor{
10                 color:#fff;
11                 background-color: #ddd;
12             }
13             .steam{
14              text-decoration:initial;
15             }
16         </style>
17     </head>
18     <body>
19          <ul id="ul">
20             <li id="a">油条</li>
21             <li id="b" class="steam">包子</li>
22             <li id="c" class="steam">米饺</li>
23             <li id="d"><a>鱼粉</a></li>
24         </ul>
25         
26         <!--按钮 onclick当点击按钮时，执行一段JavaScript代码-->
27         <button onclick="gaibianyangshi()">点击</button>
28         
29         <script>
30       
31         function gaibianyangshi() {
32         /**querySelector查询选择器**/
33             var el = document.querySelector('li.steam');
34             el.className='mycolor';
35         
36         }
37             
38         </script>
39     </body>
40 </html>

 

posted @ 2019-07-10 19:04  JackSon~鹤  阅读(1017)  评论(0)  编辑  收藏  举报