// http://seofromusa.com/wordpress-customizazion/target-blank-rel-external-nofollow/

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 nofollow") || (anchor.getAttribute("rel") == "nofollow external") || (anchor.getAttribute("rel") == "external")))
      anchor.target = "_blank";
  }
}
// window.onload = externalLinks;