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") == "external nofollow") ||
(anchor.getAttribute("rel") == "nofollow external") ||
(anchor.getAttribute("rel") == "external")))

anchor.target = "_blank";

}

}

window.onload = externalLinks;