file.js

var PasswordValidator = function () {
    var errors = [];

    return {
        errors: errors,
        validateLength: function(password) {
            if (password.length < 6) {
                errors.push('The password must be at least 6 characters long.')
            }
        },
        validate: function(password) {
            this.validateLength(password);
            return this.errors;
        }
    }
};

var UpdatePasswordForm = (function () {

    var self = this;
    var formElement = $('#updatePasswordForm');
    var passwordField = $(formElement.find('[name="password"]').first());
    var validationErrorsBox = $('.password-validation-errors');
    var passwordValidationErrorField = validationErrorsBox.find('#passwordValidationError');
    var errors = [];
    var validator = new PasswordValidator();

    return {
        renderPasswordValidationErrors: function () {

            if (validationErrorsBox.hasClass('hidden')) {
                validationErrorsBox.fadeIn(300).removeClass('hidden');
            }
            passwordValidationErrorField.text(errors);
        },
        hidePasswordValidationErrors: function () {
            $('.password-validation-errors').fadeOut(300).addClass('hidden');
        },
        validatePasswordField: function() {
            passwordField.on('keydown', function() {
                var password = this.value;
                errors = validator.validate(password);
                if (errors.length >= 1) {
                    self.renderPasswordValidationErrors();
                } else {
                    self.hidePasswordValidationErrors();
                }
                //console.log('hola');
                //passwordValidationErrorField.text('Validating!');

            });
        },
        hello: function () {
            console.log(passwordField);

        }
    };

})();

window.MatrixApp = {};
window.MatrixApp.UpdatePasswordForm = UpdatePasswordForm;