function swapImg(newImage) {
  var thumb = document.getElementById(newImage);
  var newDetailImg = thumb.getAttribute("src").replace("small","detail");
  var detail = document.getElementById("detailimg");
  var newThumbImg = detail.getAttribute("src").replace("detail","small");
  
  thumb.setAttribute("src",newThumbImg);
  detail.setAttribute("src",newDetailImg);
  
  return false;
}