function showPic(whichpic) {
	if (!document.getElementById) return true;
	var source = whichpic.getAttribute("href");
	var placeholder = document.getElementById("placeholder");
	placeholder.setAttribute("src",source);
	return false;
}
function prepareGallery() {
	preparePlaceholder();
	if (!document.getElementsByTagName) return false;
	if (!document.getElementById) return false;
	if (!document.getElementById("imagegallery")) return false;
	var gallery = document.getElementById("imagegallery");
	var links = gallery.getElementsByTagName("a");
	for ( var i=0; i < links.length; i++) {
		links[i].onclick = function() {
		  return showPic(this);
		}
	}
}

function preparePlaceholder() {
  if (!document.createElement) return false;
  if (!document.createTextNode) return false;
  var placeholder = document.createElement("img");
  placeholder.setAttribute("id","placeholder");
  placeholder.setAttribute("src","images/placeholder.jpg");
  placeholder.setAttribute("alt","my image gallery");
  var gallery = document.getElementById("imagegallery");
  gallery.parentNode.insertBefore(placeholder,gallery);
}

window.onload = prepareGallery;