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;