Event.observe(window, 'load', initPage);

function initPage()
{
  var u = new Updater();
}

var Updater = Class.create();
Updater.prototype =
{
  initialize: function()
  {
    $('update').onclick = this.eventSubmit.bindAsEventListener(this);
    $('update2').onclick = this.eventSubmit.bindAsEventListener(this);
  },

  eventSubmit: function(ev)
  {
    Event.stop(ev);
    var opt = $('update')!=Event.element(ev);
    new Ajax.Request
    (
      'foobar'+(opt?'-optimised':'')+'.html',
      {
        onSuccess: function(t)
        {
          var pieces = t.responseText.split('<!--break-->');
          Element.update($('firstdiv'),  pieces[0]);
          Element.update($('seconddiv'), pieces[1]);
        }
      }
    );
    return false;
  }
};