How to Load Items into an Infinite Loop

How to Load Items into an Infinite Loop

Can you please take a look at  This Demo  let me know how I can load items into the  ul  list as an endless list. as you can see I have this list as following code but I need to add items again and again at the end of each time list.

  2. var item = $(".thumbnail").width();
  3. var paddT = $(".thumbnail").css('margin-left');
  4. item = item + 20;
  5. $(".leftslide").on("click", function () {
  6.     $(".list-inline").animate({
  7.         left: '-=' + item + 'px'
  8.     }, 300);
  9. });
  10. $(".rightslide").on("click", function () {
  11.     $(".list-inline").animate({
  12.         left: '+=' + item + 'px'
  13.     }, 300);
  14. }); 
Thanks