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")
anchor.target = "_blank";
} 
}
window.onload=externalLinks;