function externalLinks() {
if (!document.getElementsByTagName) return;
var anchors = document.getElementsByTagName("a");
for (var i=0; i<anchors .length; i++) {
var anchor = anchors[i];
if (
	(anchor.getAttribute("href") && anchor.getAttribute("rel") == "externer-link")
   ) {
anchor.target = "_blank";
anchor.title = (anchor.title != "") ? anchor.title+" (öffnet ein neues Fenster)" : "in einem Neuen Fenster:";
}
}
}

window.onload = externalLinks;