jQuery e-mail plugin validation

jquery-email-validation.js

(function ($) {

    $.fn.validateEmail = function () {
        return this.each(function () {
            var $this = $(this);
            $this.change(function () {
                var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
                if ($this.val() == "") {
                    $this.removeClass("badEmail").removeClass("goodEmail")
                }else if(reg.test($this.val()) == false) {
                    $this.removeClass("goodEmail");
                    $this.addClass("badEmail");
                }else{
                    $this.removeClass("badEmail");
                    $this.addClass("goodEmail");
                }
            });
        });
    };
})(jQuery);