早上看到博友6点多发的一篇关于密码强度的文章（[连接](http://www.cnblogs.com/cx361/archive/2011/11/27/2264821.html)），甚是感动（周末大早上还来发文）。
我们来看看如果使用Knockout更简单的来实现密码强度的验证。
原有代码请查看：
~~~
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body>
<script type="text/javascript">
//CharMode函数
function CharMode(iN) {
if (iN >=48&& iN <=57) //数字
return1;
if (iN >=65&& iN <=90) //大写字母
return2;
if (iN >=97&& iN <=122) //小写
return4;
else
return8; //特殊字符
}
//bitTotal函数
function bitTotal(num) {
modes =0;
for (i =0; i <4; i++) {
if (num &1) modes++;
num >>>=1;
}
return modes;
}
//checkStrong函数
function checkStrong(sPW) {
if (sPW.length <=4)
return0; //密码太短
Modes =0;
for (i =0; i < sPW.length; i++) {
Modes |= CharMode(sPW.charCodeAt(i));
}
return bitTotal(Modes);
}
//pwStrength函数
function pwStrength(pwd) {
O_color ="#eeeeee";
L_color ="#FF0000";
M_color ="#FF9900";
H_color ="#33CC00";
if (pwd ==null|| pwd =='') {
Lcolor = Mcolor = Hcolor = O_color;
} else {
S_level = checkStrong(pwd);
switch (S_level) {
case0:
Lcolor = Mcolor = Hcolor = O_color;
case1:
Lcolor = L_color;
Mcolor = Hcolor = O_color;
break;
case2:
Lcolor = Mcolor = M_color;
Hcolor = O_color;
break;
default:
Lcolor = Mcolor = Hcolor = H_color;
}
document.getElementById("strength_L").style.background = Lcolor;
document.getElementById("strength_M").style.background = Mcolor;
document.getElementById("strength_H").style.background = Hcolor;
return;
}
} </script>
<form name="form1" action="">
输入密码:<input type="password" size="10" onkeyup="pwStrength(this.value)" onblur="pwStrength(this.value)">
<br>
密码强度:
<table width="217" border="1" cellspacing="0" cellpadding="1" bordercolor="#cccccc"
height="23" style='display: inline'>
<tr align="center" bgcolor="#eeeeee">
<td width="33%" id="strength_L">
弱
</td>
<td width="33%" id="strength_M">
中
</td>
<td width="33%" id="strength_H">
强
</td>
</tr>
</table>
</form>
</body>
</html>
~~~
首先我们来改善一下上面博友的验证函数为如下代码：
~~~
var Page = Page || {};
Page.Utility = Page.Utility || {};
Page.Utility.Registration = Page.Utility.Registration || {};
//获取密码强度
Page.Utility.Registration.getPasswordLevel = function (password) {
if (password == null || password == '')
return 0;
if (password.length <= 4)
return 0; //密码太短
var Modes = 0;
for (i = 0; i < password.length; i++) {
Modes |= CharMode(password.charCodeAt(i));
}
return bitTotal(Modes);
//CharMode函数
function CharMode(iN) {
if (iN >= 48 && iN <= 57) //数字
return 1;
if (iN >= 65 && iN <= 90) //大写字母
return 2;
if (iN >= 97 && iN <= 122) //小写
return 4;
else
return 8; //特殊字符
}
//bitTotal函数
function bitTotal(num) {
modes = 0;
for (i = 0; i < 4; i++) {
if (num & 1) modes++;
num >>>= 1;
}
return modes;
}
};
~~~
然后来创建View Model，但是引用Knockout之前，我们首先要引用Knockout的Js类库（具体介绍请查看[Knockout应用开发指南](http://www.cnblogs.com/TomXu/archive/2011/11/21/2257154.html)的系列教程）
View model代码如下：
~~~
var viewModel = {
Password: ko.observable(""),
Ocolor: "#eeeeee"
};
~~~
对于密码强度以及颜色的值依赖于密码字符串的值，所以我们需要为他们声明依赖属性，代码如下：
~~~
viewModel.PasswordLevel = ko.dependentObservable(function () {
return Page.Utility.Registration.getPasswordLevel(this.Password());
}, viewModel);
viewModel.Lcolor = ko.dependentObservable(function () {
//根据密码强度判断第一个格显示的背景色
return this.PasswordLevel() == 0 ? this.Ocolor : (this.PasswordLevel() == 1 ? "#FF0000" : (this.PasswordLevel() == 2 ? "#FF9900" : "#33CC00"))
}, viewModel);
viewModel.Mcolor = ko.dependentObservable(function () {
//根据密码强度判断第二个格显示的背景色
return this.PasswordLevel() < 2 ? this.Ocolor : (this.PasswordLevel() == 2 ? "#FF9900" : "#33CC00")
}, viewModel);
viewModel.Hcolor = ko.dependentObservable(function () {
//根据密码强度判断第三个格显示的背景色
return this.PasswordLevel() < 3 ? this.Ocolor : "#33CC00"
}, viewModel);
~~~
然后使用applyBindings方法将view model绑定到该页面，你可以使用jQuery的ready函数来执行该绑定代码，也可以在页面最下方执行绑定代码，我们这里使用了jQuery，代码如下：
~~~
$((function () {
ko.applyBindings(viewModel);
}));
~~~
最后，我们再看看这些值怎么动态绑定到HTML元素上的，请查看如下代码（其中使用了afterkeydown代替了onKeyUp和onBlur）：
~~~
<form name="form1" action="">
输入密码:
<input type="text" size="10" data-bind="value:Password, valueUpdate: 'afterkeydown'">
<br>
密码强度:
<table width="217" border="1" cellspacing="0" cellpadding="1" bordercolor="#cccccc"
height="23" style='display: inline'>
<tr align="center" bgcolor="#eeeeee">
<td width="50"data-bind="style: { backgroundColor: Lcolor }">弱</td>
<td width="50"data-bind="style: { backgroundColor: Mcolor }">中</td>
<td width="50"data-bind="style: { backgroundColor: Hcolor }">强</td>
</tr>
</table>
</form>
~~~
然后就OK，运行代码查看，一模一样的功能展示出来了。
如果去掉为验证而改善的代码，总代码肯定是比原有的方式少的。
完整版代码如下：
~~~
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<script type="text/javascript" src="http://knockoutjs.com/js/jquery-1.4.2.min.js"></script>
<script type="text/javascript" src="http://knockoutjs.com/js/jquery.tmpl.js"></script>
<script type="text/javascript" src="http://knockoutjs.com/js/knockout-1.2.1.js"></script>
</head>
<body>
<script type="text/javascript">
var Page = Page || {};
Page.Utility = Page.Utility || {};
Page.Utility.Registration = Page.Utility.Registration || {};
//获取密码强度
Page.Utility.Registration.getPasswordLevel =function (password) {
if (password ==null|| password =='')
return0;
if (password.length <=4)
return0; //密码太短
var Modes =0;
for (i =0; i < password.length; i++) {
Modes |= CharMode(password.charCodeAt(i));
}
return bitTotal(Modes);
//CharMode函数
function CharMode(iN) {
if (iN >=48&& iN <=57) //数字
return1;
if (iN >=65&& iN <=90) //大写字母
return2;
if (iN >=97&& iN <=122) //小写
return4;
else
return8; //特殊字符
}
//bitTotal函数
function bitTotal(num) {
modes =0;
for (i =0; i <4; i++) {
if (num &1) modes++;
num >>>=1;
}
return modes;
}
};
var viewModel = {
Password: ko.observable(""),
Ocolor: "#eeeeee"
};
viewModel.PasswordLevel = ko.dependentObservable(function () {
return Page.Utility.Registration.getPasswordLevel(this.Password());
}, viewModel);
viewModel.Lcolor = ko.dependentObservable(function () {
//根据密码强度判断第一个格显示的背景色
returnthis.PasswordLevel() ==0?this.Ocolor : (this.PasswordLevel() ==1?"#FF0000" : (this.PasswordLevel() ==2?"#FF9900" : "#33CC00"))
}, viewModel);
viewModel.Mcolor = ko.dependentObservable(function () {
//根据密码强度判断第二个格显示的背景色
returnthis.PasswordLevel() <2?this.Ocolor : (this.PasswordLevel() ==2?"#FF9900" : "#33CC00")
}, viewModel);
viewModel.Hcolor = ko.dependentObservable(function () {
//根据密码强度判断第二个格显示的背景色
returnthis.PasswordLevel() <3?this.Ocolor : "#33CC00"
}, viewModel);
$((function () {
ko.applyBindings(viewModel);
}));
</script>
<form name="form1" action="">
输入密码:<input type="text" size="10" data-bind="value:Password, valueUpdate: 'afterkeydown'">
<br>
密码强度:
<table width="217" border="1" cellspacing="0" cellpadding="1" bordercolor="#cccccc"
height="23" style='display: inline'>
<tr align="center" bgcolor="#eeeeee">
<td width="50" id="strength_L" data-bind="style: { backgroundColor: Lcolor }">
弱
</td>
<td width="50" id="strength_M" data-bind="style: { backgroundColor: Mcolor }">
中
</td>
<td width="50" id="strength_H" data-bind="style: { backgroundColor: Hcolor }">
强
</td>
</tr>
</table>
</form>
</body>
</html>
~~~
