(function() {
  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") && anchor.getAttribute("rel").indexOf("external") > -1) {
      anchor.target = "_blank";
    }
  }
})()