这篇文章给大家介绍JavaScript中怎么评估用户输入密码的强度，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
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 PagePage = Page || {}; PagePage.Utility = Page.Utility || {}; PagePage.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***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); }));***，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 PagePage = Page || {}; PagePage.Utility = Page.Utility || {}; PagePage.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***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>关于JavaScript中怎么评估用户输入密码的强度就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
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