初学js正则表达式之密码强度验证

<!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>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>passwordCheck</title>
<script type="text/javascript" src="Js/jquery1.6.1.js"></script>
<script type="text/javascript">
    $(function() {
        $('#pwd').keyup(function() {
            var val = $(this).val();
            isDigit(val);
        });  

        function isDigit(s) {
            var pattern_d = /^\d+$/;            //全数字
            var pattern_s = /^[A-Za-z]+$/       //全字符
            var pattern_w = /^\w+$/;            //数字或者字符
            var pattern_W = /^\W+$/             //全非数字也非字符
            var pattern_r = /^\w+\W+[\w\W]*\w+$/    //以字母或者数字开头结尾的字符串
            var html = '';
            var x = 0;
            var y = 0;  

            $('#user').html(s);
            if(pattern_W.exec(s)) {
                html += '非数字也非字符<br />';
                x = 0;
                y = 0;
            }
            if(pattern_w.exec(s)) {
                html += '数字或者字符<br />';
                y = 1;
            }
            if(pattern_d.exec(s)) {
                html += '全数字<br />';
                x = 1;
                y = 0;
            }
            if(pattern_s.exec(s)) {
                html += '全字符<br />';
                x = 2;
                y = 0;
            }
            if(pattern_r.exec(s)) {
                html += '以字母或者数字开头结尾的字符串<br />';
                x = 3;
                y = 2;
            }
            if( y === 0 && x === 0) {
                html += '密码格式错误<br />';
            }
            if( x > 0 && y === 0) {
                html += '安全级别《低》<br />';
            }
            if( x === 0 && y === 1) {
                html += '安全级别《中》<br />';
            }
            if( y === 2) {
                html += '安全级别《高》<br />';
            }
            html += x + '<br />' + y;
            $('#password').html(html);
        };
    });
</script>
</head>  

<body>
<form action="#" method="#">
    用户名：<input type="text" name="" /><span id="user"></span><br />
    密码：<input type="password" name="" id="pwd" /><span id="password"></span><br />
</form>
</body>
</html>