// element for slider items (thumbnails)
var SLIDER_ITEM="li";
// selector for visible slider items 
var SLIDER_ITEM_VISIBLE="li:visible";
// class for backward scroll action
var PREV_BUTTON=".sliderPrev";
//class for forward scroll action
var NEXT_BUTTON=".sliderNext";

	function slide(event) {
	event.preventDefault();
	var slider=$(this).parent();
	var goForward=true;
	var visibleThumbs=slider.find(SLIDER_ITEM_VISIBLE);
	if($(this).hasClass(NEXT_BUTTON)) {
		if(visibleThumbs.eq(1).next(SLIDER_ITEM).get(0)) {
			visibleThumbs.eq(0).hide();
			visibleThumbs.eq(1).next(SLIDER_ITEM).show();
		}
	} else if ($(this).hasClass(PREV_BUTTON)) {
		if(visibleThumbs.eq(0).prev(SLIDER_ITEM).get(0)) {
			visibleThumbs.eq(1).hide();
			visibleThumbs.eq(0).prev(SLIDER_ITEM).show();
		}
	}	
}
$(PREV_BUTTON).click(slide);
$(NEXT_BUTTON).click(slide);