gistfile1.html

<button class="replybutton" data-origional="123" data-parent="123">Reply</button>
<script>

$('.replybutton').on('click', function(){
  $(this).addClass('loading'); // a class that adds a no-repeat right-aligned background of a spinning giff... give it some padding so it appears 'in the button'.
   if ($(this).is(":visible")) {
            $("#post" + $(this).data("parent")).slideUp();
        } else {
            $("#post" + $(this).data("parent")).hide();
            $("#post" + $(this).data("parent")).load("/reply?parentPost=" + $(this).data("parent") + "&originalPost=" + $(this).data("origional"), function () {
              $("#post" + $(this).data("parent")).slideDown();
              $(this).removeClass("loading");
            });
        }
}


</script>