$(document).ready(function () {
    $(".chzn-select").chosen().change(function () {
        var selectedItem = $(".chzn-select option:selected");
        var url = selectedItem.attr("url");
        var selectedValue = selectedItem.text();
        var defaultValue = $(".chzn-select").attr("data-placeholder");

        if (selectedValue && selectedValue != defaultValue) {
            if (!url) {
                alert('Option without url defined.');
            }
            else {
                window.location.href = url;
            }
        }
    });
});