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;