var onEnterHandler = null;

function onEnter( obj_id, handler ){
  var obj = document.getElementById(obj_id);
  if ( obj.addEventListener ){
    obj.addEventListener('keypress', isEnter, false);
  }
  else if ( obj.attachEvent ){
    obj.attachEvent('onkeypress', isEnter);
  }
  onEnterHandler = handler;
}


function isEnter( evnt ){
  var code = null;
  if ( !evnt ) evnt = window.event;
  if ( evnt.keyCode ){
    code = evnt.keyCode;
  }
  else if ( evnt.which ){
    code = evnt.which;
  }
  if ( code == 13 ){
    eval(onEnterHandler);
  }
}