function setPostcard(obj, val) {
	var imgSrc = obj.getHref();
	document.getElementById('postcard_preview').getFirstChild().setSrc(imgSrc);
	document.getElementById('selected_postcard').setValue(val);
}

for (var i = 0; i < 9; i++) {
	if (document.getElementById('postcard' + i) !== null) {
		document.getElementById('postcard' + i).getFirstChild().addEventListener('click', function(){ setPostcard(this, i); return false; });
	}
}