var registration = {
    
  init: function() {
    if ($('row_other') && $('register_business_sector_id')) {
      
      var selIndex = $('register_business_sector_id').selectedIndex;
      var option = $('register_business_sector_id').options[selIndex].text;
            
      if (option!='Other') $('row_other').setStyle({display:'none'});
      
      Event.observe('register_business_sector_id', 'change', registration.update, false);
      
      
    }
  },

  update: function(event) {
    var selIndex = $('register_business_sector_id').selectedIndex;
    var option = $('register_business_sector_id').options[selIndex].text;
    
    if (option=='Other') {
      $('row_other').setStyle({display:'block'});
    } else {
      $('row_other').setStyle({display:'none'});
      $('register_other').value='';
    }
  }
}

document.observe( "dom:loaded", registration.init );