window.onload = prepareLinks;
function prepareLinks() {
	var links = document.getElementsByTagName("a");
	for (var i=0; i<links.length; i++) {
		if (links[i].getAttribute("class") == "popup") {
			links[i].onclick = function() {
				popUp(this.getAttribute("href"));
				return false;
			}
		}
	}
}
function popUp(url) {
	window.open(url,"popup","width=850,height=500");
}