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"; 
    }
  } 
} 
addLoadEvent(externalLinks);


function addLoadEvent(func)
{ 
  var oldonload = window.onload;
  if (typeof window.onload != 'function'){
      window.onload = func;
  } else {
    window.onload = function(){
    oldonload();
    func();
    }
  }

}