var ChangeTab = {
    /**
     * Смена вкладок
     * @author ilyabazhenov
     */
    changeTab : function (element) {
        if ( ! element.hasClass("active") )
        {
            var what_to_hide = element.parent().find('.active').removeClass('active').attr('id').replace('show-', '');
            var what_to_show = element.attr('id').replace("show-", "");
            
            if (what_to_show == 'audio')
            {
            	$(".block.main-book.book").removeClass("book").addClass("music");
            }
            else if (what_to_show == 'ebook')
            {
            	$(".block.main-book.music").removeClass("music").addClass("book");
            }
            element.addClass('active');

            $(".content-items ."+what_to_hide).hide();
            $(".content-items ."+what_to_show).show();
        }
    }
}