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.title ="Link opens in a new window";
  anchor.target = "_blank"; 
    }
 } 
} 
window.onload = externalLinks;