var httpStatusCode = { unauthorized: 401, forbidden: 403, notAllowed: 405 };

function onError(request, status, statusCode) {
  var httpStatus = parseInt(request.status);

  switch (httpStatus) {
    case httpStatusCode.forbidden:
      // ...
      break;
    case httpStatusCode.notAllowed:
      // ...
      break;
    case httpStatusCode.unauthorized:
      // ...
      break;
    default:
      // ...
      break;
  }  
}

function onSuccess(data, status, request) {
  // если что-то там вернулось
}

$.ajax({ error: onError, success: onSuccess, url: encodeURI(urls) });