JavaScript实现记住密码功能

用js实现记住密码功能，但是前端记住密码不安全，最好还是不要用。我感觉这个记住密码应该是通过与后台建立一个会话来实现。
这个效果的测试地址在：http://ofoyou.com/blog/rePassword.html
<!DOCTYPE HTML>

<head>

    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

    <title>js COOKIE 记住帐号或密码</title>

    <script type="text/javascript">

    //点击登录时触发客户端事件

    function SetPwdAndChk() {

        //取用户名

        var usr = document.getElementById('txtUserName').value;

        alert(usr);

        //将最后一个用户信息写入到Cookie

        SetLastUser(usr);

        //如果记住密码选项被选中

        if (document.getElementById('chkRememberPwd').checked == true) {

            //取密码值

            var pwd = document.getElementById('txtPassword').value;

            alert(pwd);

            var expdate = new Date();

            expdate.setTime(expdate.getTime() + 14 * (24 * 60 * 60 * 1000));

            //将用户名和密码写入到Cookie

            SetCookie(usr, pwd, expdate);

        } else {

            //如果没有选中记住密码,则立即过期

            ResetCookie();

        }

    }

    function SetLastUser(usr) {

        var id = "49BAC005-7D5B-4231-8CEA-16939BEACD67";

        var expdate = new Date();

        //当前时间加上两周的时间

        expdate.setTime(expdate.getTime() + 14 * (24 * 60 * 60 * 1000));

        SetCookie(id, usr, expdate);

    }

    //用户名失去焦点时调用该方法

    function GetPwdAndChk() {

        var usr = document.getElementById('txtUserName').value;

        var pwd = GetCookie(usr);

        if (pwd != null) {

            document.getElementById('chkRememberPwd').checked = true;

            document.getElementById('txtPassword').value = pwd;

        } else {

            document.getElementById('chkRememberPwd').checked = false;

            document.getElementById('txtPassword').value = "";

        }

    }

    //取Cookie的值

    function GetCookie(name) {

        var arg = name + "=";

        var alen = arg.length;

        var clen = document.cookie.length;

        var i = 0;

        while (i < clen) {

            var j = i + alen;

            //alert(j);

            if (document.cookie.substring(i, j) == arg) return getCookieVal(j);

            i = document.cookie.indexOf(" ", i) + 1;

            if (i == 0) break;

        }

        return null;

    }

    function getCookieVal(offset) {

        var endstr = document.cookie.indexOf(";", offset);

        if (endstr == -1) endstr = document.cookie.length;

        return unescape(document.cookie.substring(offset, endstr));

    }

    //写入到Cookie

    function SetCookie(name, value, expires) {

        var argv = SetCookie.arguments;

        //本例中length = 3

        var argc = SetCookie.arguments.length;

        var expires = (argc > 2) ? argv[2] : null;

        var path = (argc > 3) ? argv[3] : null;

        var domain = (argc > 4) ? argv[4] : null;

        var secure = (argc > 5) ? argv[5] : false;

        document.cookie = name + "=" + escape(value) + ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) + ((path == null) ? "" : ("; path=" + path)) + ((domain == null) ? "" : ("; domain=" + domain)) + ((secure == true) ? "; secure" : "");

    }

    function ResetCookie() {

        var usr = document.getElementById('txtUserName').value;

        var expdate = new Date();

        SetCookie(usr, null, expdate);

    }

    </script>

</head>

<body>

    <form id="form1">

        <div>

            用户名:

            <input type="text" id="txtUserName" onblur="GetPwdAndChk()">

            <br> 密码：

            <input type="password" id="txtPassword">

            <input type="checkbox" id="chkRememberPwd" />记住密码

            <br>

            <input type="button" OnClick="SetPwdAndChk()" value="进入" />

        </div>

    </form>

</body>

</html>