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;