A non-block promise wrapper fro axios/fetch

promise-wrapper.ts

import type { AxiosError, AxiosPromise } from 'axios';

type Result<T> = [AxiosError, null] | [null, T];
type AllResult<T> = [AxiosError, null] | [null, T[]];

/**
 * Wraps an Axios promise to return a tuple with either the error or the response data.
 *
 * @template T - The type of the response data.
 * @param {AxiosPromise<T>} promise - The Axios promise to wrap.
 * @returns {Promise<Result<T>>} A promise that resolves to a tuple containing either the error or the response data.
 *
 * @example
 * const [error, data] = await promiseWrapper(axios.get('/api/data'));
 * if (error) {
 *   console.error('Request failed', error);
 * } else {
 *   console.log('Request succeeded', data);
 * }
 */
export const promiseWrapper = async <T>(promise: AxiosPromise<T>): Promise<Result<T>> => {
  try {
    const response = await promise;
    return [null, response.data];
  } catch (error) {
    return [error as AxiosError, null];
  }
};

/**
 * Wraps multiple promises and returns a tuple with either the first error encountered or an array of all response data.
 *
 * @template T - The type of the response data.
 * @param {Iterable<Promise<Result<any>>>} wrappedPromises - An iterable of wrapped promises to resolve.
 * @returns {Promise<AllResult<any>>} A promise that resolves to a tuple containing either the first error encountered or an array of all response data.
 *
 * @example
 * const promises = [promiseWrapper(axios.get('/api/data1')), promiseWrapper(axios.get('/api/data2'))];
 * const [error, data] = await promiseWrapperAll(promises);
 * if (error) {
 *   console.error('One or more requests failed', error);
 * } else {
 *   console.log('All requests succeeded', data);
 * }
 */
export const promiseWrapperAll = async <T>(
  wrappedPromises: Iterable<Promise<Result<any>>>
): Promise<AllResult<any>> => {
  const results = await Promise.all(wrappedPromises);
  const errors = results.filter(([error]) => error !== null) as [AxiosError, null][];

  if (errors.length > 0) {
    return [errors[0][0], null];
  }

  return [null, results.map(([, data]) => data as T)];
};


// EXAMPLE
const fetchUsers = promiseWrapper(axios.get('/users'));

const [error, users] = await fetchUsers();

if (error) {
  console.error(error);
  return;
}

console.log(users);