function externalLinks() {
  if (!document.getElementsByTagName) return;
  var anchors = document.getElementsByTagName("a");
  for (var i=0; i<anchors.length; i++) {
    var anchor = anchors[i];
    var target = anchor.getAttribute("href");
    if (target)  {
      if (target.indexOf("http") != -1)  {
        anchor.target = "_blank";
      }
    }
  }
}
window.onload = externalLinks;