window.onload = function() {
	// check to see that the browser supports the getElementsByTagName method
	// if not, exit the loop
	if (!document.getElementsByTagName) {
		return false;
	}
	// create an array of objects of each link in the document
	var popuplinks = document.getElementsByTagName("a");
	// loop through each of these links (anchor tags)
	for (var i=0; i < popuplinks.length; i++) {
		// if the link has a class of "popup"...
		if (popuplinks[i].className == "popup") {
			// add an onclick event on the fly to pass the href attribute
			// of the link to our second function, openPopUp
			popuplinks[i].onclick = function() {
				openPopUp(this.getAttribute("href"));
				return false;
			}
		}
	}
}

function openPopUp(linkURL) {
	window.open(linkURL,'popup','width=770, height=700')
}