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;

// call this script by using rel="external" in a link in lieu of target="_blank"