function init() {
 var links = document.getElementsByTagName('a');
 for (var i=0;i < links.length;i++) {
  if (links[i].className == 'external') {
   links[i].onclick = function() {
    window.open(this.href);
    return false;
   };
  } 
 }
}
 
if(document.childNodes) {
 window.onload = init;
}