Cancelable promise

Cancelable promise

export interface CancelablePromise<T> {
  promise: Promise<T>;
  cancel(): void;
}

/**
 * Make a Promise cancelable
 */
export const makeCancelablePromise = <T>(promise: Promise<T>): CancelablePromise<T> => {
  let hasCanceled = false;

  const wrappedPromise = new Promise<T>((resolve, reject) => {
    promise.then(
      val => hasCanceled ? reject({ isCanceled: true }) : resolve(val),
      error => hasCanceled ? reject({ isCanceled: true }) : reject(error)
    );
  });

  return {
    promise: wrappedPromise,
    cancel() {
      hasCanceled = true;
    }
  };
};