使用Knockout.js重构密码强度验证

Knockout.js实现密码强度验证

接下来探讨如何利用Knockout框架更简洁地实现密码强度的验证逻辑。

原始的实现代码可以参考之前的示例：

 
<!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>

优化验证函数与视图模型

首先，我们对上述验证函数进行改进，优化后的代码如下：

 
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;
} 
}; 

接下来创建视图模型（ViewModel）。在引入Knockout之前，需先加载Knockout的JavaScript库（详细教程请参考Knockout应用开发指南系列文章）。

代码示例如下：

 
var viewModel = {
Password: ko.observable(""),
Ocolor: "#eeeeee"
}; 
针对密码强度及其对应的颜色值，由于它们依赖于密码字符串的状态，因此需要声明依赖属性，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);
随后，使用applyBindings方法将视图模型绑定到页面。可以通过jQuery的ready函数执行绑定，或在页面底部直接执行。此处采用jQuery方式，代码如下：
$((function () {
ko.applyBindings(viewModel);
})); 

HTML元素动态绑定

最后，观察这些值如何动态绑定到HTML元素上。注意此处使用了afterkeydown事件替代了原有的onKeyUp和onBlur，代码如下：

 
<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>

完成上述步骤后，运行代码即可看到与原功能完全一致的效果展示。

若移除为验证而优化的冗余代码，总代码量显然比原有方式更少。

完整的代码示例如下：

 
<!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>