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;