function externalLinks() {
	if (!document.getElementsByTagName) return;

	var anchors = document.getElementsByTagName("a");
	for (var i=0; i<anchors.length; i++) {
			var anchor = anchors[i];
			var relvalue = anchor.getAttribute("rel");

			if (anchor.getAttribute("href")) {
					var external = /external/;
					var relvalue = anchor.getAttribute("rel");
					if (external.test(relvalue)) { anchor.target = "_blank"; }
			}
	}
}

window.onload = externalLinks;