var dom = new Object();
dom.event = new Object();

dom.event.addEventListener = function(elm, type, func, useCapture){
  if(!elm){ return false;}
  if(!useCapture){ useCapture = false; }
  if(elm.addEventListener){
    elm.addEventListener(type, func, false);
  }else if(elm.attachEvent){
    elm.attachEvent('on'+type, func);
  }else{
    return false;
  }
  return true;
};

dom.event.target = function(evt){
  if(evt && evt.target){
    if(evt.target.nodeType == 3){
      return evt.target.parentNode;
    }else{
      return evt.target
    }
  }else if(window.event && window.event.srcElement){
    return window.event.srcElement;
  }else{
    return nil;
  }
};
function getTarget(evt){
  if(evt && evt.target){
    return evt.target;
  }else if(window.event && window.event.srcElement){
    return window.event.srcElement;
  }
}

function erase(evt){
  var this_target = getTarget(evt);
  if(this_target.value == this_target.defaultValue){
    this_target.value = '';
  }
}

function clearChildNodes(elm){
  while(elm.hasChildNodes()){
    elm.removeChild(elm.lastChild);
  }
}