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;