$(document).ready(function() {
    Sys.WebForms.PageRequestManager.getInstance().add_endRequest(setupSlider);
    setupSlider();
});

function setupSlider() {
    var kids = $('.itemContainer').children().length;
    var totalWidth = kids * $('.item').outerWidth(true);
    $('.itemContainer').css("width", totalWidth);

    if ($("#slider").slider) {
        $("#slider").slider({
            value: 0,
            min: 0,
            max: totalWidth - (4 * $('.item').outerWidth(true)),
            step: $('.item').outerWidth(true),
            slide: function(event, ui) {
                $(".itemContainer").css("left", (-1 * ui.value));
            }
        });
    }
}