Cancellable promises

cancellable-promises.js

recordRetriever.retrieveAsync = function (query) {
  var deferred = Q.defer();

  server.doPagedRetrieveWithCallback(query, 0, function (err, result) {
    // wire up deferred.resolve and deferred.reject.
    // recurse appropriately, increasing pagination,
    // UNLESS deferred.isCancelled.
  });

  deferred.promise.cancel = deferred.cancel;
  return deferred.promise;
};