jQuery.fn.fadeToggle = function(speed, easing, callback) {
   return this.animate({opacity: 'toggle'}, speed, easing, callback);
};
function subscribe() {
    var eml = $('#newsletter-email').val();
    $.post("ajax_newsletter.php", { email: eml }, function(response){
        var response = eval('(' + response + ')');
        if (response.error != '') {alert(response.error);}
        else {alert('Ďakujeme, Váš e-mail bol zaradený do nášho newslettra !');}
    });
}