function prepareGallery() {

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);
}
links[i].onkeypress = links[i].onclick;
}

}

function showPic(whichpic) {

if (!document.getElementById("placeholder")) return false;

var newsource = whichpic.getAttribute("href");
var placeholder = document.getElementById("placeholder");

placeholder.setAttribute("src", newsource);

return false;

}

addLoadEvent(prepareGallery);