function externaliseLinks() {
  var links = document.getElementsByTagName("A");
  for(var x=0; x<links.length; x++) {
    var h = links[x].rel;
    if(h=="external") {
      links[x].onclick=function() {
        window.open(this.href, "_blank");
        return false;
      }
    }
  }
}

//Run code on page load
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

//addLoadEvent(nameOfSomeFunctionToRunOnPageLoad);
/*
addLoadEvent(
	externaliseLinks();
);
*/

addLoadEvent(function() {
  /* more code to run on page load */
  externaliseLinks();
});