就是男默女泪的立flag!
1 <!DOCTYPE html>
2 <html lang="en">
3 <head>
4 <meta charset="UTF-8">
5 <title>Title</title>
6 <style>
7 .video-box{
8 width: 1000px;
9 height: 500px;
10 background-color: skyblue;
11 margin: 50px auto;
12 }
13 body.night{
14 background-color: #333;
15 color: #fff ;
16 }
17 body.night button{
18 background-color: #ccc;
19 color:#fff;
20 }
21
22 </style>
23 <script>
24 window.onload = function () {
25 var btn = document.getElementsByTagName('button');
26 var flag = false;
27 btn[0].onclick = function () {
28 if(!flag) {
29 document.body.className = "night";
30 btn[0].innerHTML = "开灯";
31 }else {
32 document.body.className = "";
33 btn[0].innerHTML = "关灯";
34 }
35 flag = !flag;
36 }
37
38 // var flag = true;
39 // btn[0].onclick = function () {
40 // flag = !flag;
41 // if(!flag) {
42 // document.body.className = "night";
43 // btn[0].innerHTML = "开灯";
44 // }else {
45 // document.body.className = "";
46 // btn[0].innerHTML = "关灯";
47 // }
48 //
49 // }
50 }
51 </script>
52 </head>
53 <body>
54 <button>关灯</button>
55 <h2>页面的文字</h2>
56 <div class="video-box"></div>
57 </body>
58 </html>
