function doPageLoad() {
  document.getElementById("url").value= window.location.href;
}

function addEvent(obj, evType, fn){ 
  if (obj.addEventListener){ 
    obj.addEventListener(evType, fn, false); 
    return true; 
  } else if (obj.attachEvent){ 
    var r = obj.attachEvent("on"+evType, fn); 
    return r; 
  } else { 
    return false; 
  } 
}
addEvent(window, 'load', doPageLoad);