$(document).ready(function(){
    var cesta = './resources/slider/';
    run(5000, 5);

    function run(interval, frames) {
        var cislo = 0;
        var item = $('.slider');
        func();

        function func() {
            cislo++;
            if(cislo == frames) { cislo = 0; }

            item.fadeOut(1000, function() {
                item.css('background-image', 'url(' + cesta + 'slider_' + cislo + '.jpg)').fadeIn(1000, function() {
                });
            });

            window.setInterval(func, interval);
        }
    }

});