Beautiful password validation from stackexchange, 8 chars, 1 upper, 1 lower, 1 special

jquery password validation

// Hold functions related to client side password validation
var password = function () {
    var minPasswordLength = 8;

    var _hasLowerCase = /[a-z]/;
    var _hasUpperCase = /[A-Z]/;
    var _hasDigit = /\d/;
    var _hasNonWord = /(_|[^\w\d])/;

    var password = [];
    var password2 = [];

    var email = [];
    var vanity = [];

    var error = $('<span class="pw-error"></span>');
    var error2 = $('<span class="pw-error">Passwords do not match.</span>');

    var enableForm = function () {
        $('input[type="submit"]').removeAttr('disabled');
    };

    // Enforces that password2 = password, and display an error message if it does not
    var mustMatch = function () {
        error2.detach();

        if (password.val().length == 0) { return; }

        if (password.val() != password2.val()) {
            password2.after(error2);

            return;
        }

        enableForm();
    };

    // Counts the # of unique characters in this password
    var uniqueCharacters = function (pw) {
        var hash = {};

        for (var i = 0; i < pw.length; i++)
            hash[pw[i]]++;

        var ret = 0;

        for (var p in hash) {
            if (hash.hasOwnProperty(p)) {
                ret++;
            }
        }

        return ret;
    };

    // Enforces server side password rules, inline on the client for convenience
    var enforceRules = function () {
        error.detach();

        var pw = password.val().toLowerCase();

        if (pw.length == 0) { return; }

        var hasLower = _hasLowerCase.test(password.val());
        var hasUpper = _hasUpperCase.test(password.val());
        var hasDigit = _hasDigit.test(password.val());
        var hasNonWord = _hasNonWord.test(password.val());
        var charClassCount = 0;

        if (hasLower) charClassCount++;
        if (hasUpper) charClassCount++;
        if (hasDigit) charClassCount++;
        if (hasNonWord) charClassCount++;

        if (charClassCount < 3) {
            var nag = 'Add';
            if (!hasUpper) nag += ' upper case,';
            if (!hasLower) nag += ' lower case,';
            if (!hasDigit) nag += ' numbers,';
            if (!hasNonWord) nag += ' special characters,';

            nag = nag.substr(0, nag.length - 1) + '.';

            nag = nag.replace(/(.*),/, '$1, or');

            error.text(nag);

            password.after(error);
            return;
        }

        if (email.length != 0 && email.val().length > 0 && (pw.indexOf(email.val().toLowerCase()) != -1 || email.val().toLowerCase().indexOf(pw) != -1)) {
            error.text('Cannot match your account name.');

            password.after(error);
            return;
        }

        if (vanity.length != 0 && vanity.val().length != 0 && (pw.indexOf(vanity.val().toLowerCase()) != -1 || vanity.val().toLowerCase().indexOf(pw) != -1)) {
            error.text('Cannot match your vanity identifier.');

            password.after(error);
            return;
        }

        var uniqueChars = uniqueCharacters(password.val());

        if (uniqueChars < minPasswordLength) {
            var remaining = minPasswordLength - uniqueChars;

            error.text('Must contain at least ' + remaining + ' more unique characters.');

            password.after(error);
            return;
        }

        // don't bother enforcing this until the password is actually *good*
        mustMatch();
    };

    return {
        // hook all password/password2 fields on a page
        init: function () {
            password = $('input[name="password"]');
            password2 = $('input[name="password2"]');

            email = $('input[name="email"]');
            vanity = $('input[name="vanity"]');

            if (password.length == 0 || password2.length == 0) return;

            password.keyup(enforceRules);
            password2.keyup(enforceRules);
            if (vanity.length != 0) vanity.blur(enforceRules);
        }
    };
} ();