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";
 }
 
 var maps = document.getElementsByTagName("area");
 for (var i=0; i<maps.length; i++) {
	   var map = maps[i];
	   if (map.getAttribute("href") && map.className === "external")
	     map.target = "_blank";
	 } 

}
window.onload = externalLinks;