JavaScript基础插曲-练习

1. <script type="text/javascript">
2.     var msg = ' Hello ';
3.     msg = msg.replace(/^\s+/, "").replace(/&\s+/, '');
4.     alert(msg);
5. </script>

1. <script type="text/javascript">
2.     window.onload = function () {
3.         //这里为文本框注册一个键盘键按下后弹起的事件
4.         document.getElementById('txtPassword').onkeyup = function () {
5.             var tds = document.getElementById('tb1').getElementsByTagName('td');
6.             //初始化颜色
7.             for (var i = 0; i <tds.length; i++) {
8.                 tds[i].style.backgroundColor = '';
9.             }
10.             //1:获取用户输入的内容
11.             var val = this.value;
12.             if (val.length > 0) {
13.             //2:根据用户输入的密码，来效验密码的强度。
14.             var pwdLvl = getPasswordLever(val);
15.             //3:改变下面显示的强度。
16.             switch (pwdLvl) {
17.                 case 0:
18.                 case 1:
19.                 case 2:
20.                     //弱
21.                     tds[0].style.backgroundColor = 'red';
22.                     break;
23.                 case 3:
24.                 case 4:
25.                     //中
26.                     tds[0].style.backgroundColor = 'orange';
27.                     tds[1].style.backgroundColor = 'orange';
28.                     break;
29.                 case 5:
30.                     //强
31.                     tds[0].style.backgroundColor = 'green';
32.                     tds[1].style.backgroundColor = 'green';
33.                     tds[2].style.backgroundColor = 'green';
34.                     break;
35.                 default:
36.             }
37.             }
38.  
39.         };
40.     };
41.     //这里是申明了一个匿名函数，通过这个匿名函数来判断密码的强度。
42.     function getPasswordLever(user_pwd) {
43.         //下面是通过正则表达式的match()方法来判断输入的密码中是否有满足的指定条件。
44.         var lvl = 0;
45.         //1:含有数字，强度+1
46.         if (user_pwd.match(/\d+/)) {
47.             lvl++;
48.         }
49.         //2：含有小写字母，强度+1
50.         if (user_pwd.match(/[a-z]+/)) {
51.             lvl++;
52.         }
53.         //3:含有大写字母，强度+1
54.         if (user_pwd.match(/[A-Z]+/)) {
55.             lvl++;
56.         }
57.         //4:含有特殊符号，强度+1
58.         if (user_pwd.match(/[^0-9a-zA-Z]+/)) {
59.             lvl++;
60.         }
61.         //5:密码的长度超过6位，强度+1
62.         if (user_pwd.length > 6) {
63.             lvl++;
64.         }
65.         return lvl;
66.     }
67. </script>