async_helpers.js

// Taken from
// https://advancedweb.hu/how-to-use-async-functions-with-array-filter-in-javascript/
// and
// https://patrickmuff.ch/blog/async-filter-array-typescript/

/**
 * @param  {Array} array The array to perform the map on
 * @param  {Function} callback to be performed on each array element
 * @return {Promise} Which returns an array of the results, in order.
 */
function mapAsync(array, callback) {
  return Promise.all(array.map(callback));
}
/**
 * @param  {Array} array The array to filter
 * @param  {Function} callback The async function that MUST return truthy/falsey values to filter the array
 * @return {Promise} Which returns a the filtered array
 */
async function filterAsync(array, callback) {
  // filterMap will have an array of values (ideally booleans but may be simply truthy/falsey)
  // this matches the length of array
  // this happens asynchronously
  const filterMap = await mapAsync(array, callback);

  // then we simply filter by comparing the mapped array with the one passed in.
  // eslint-disable-next-line security/detect-object-injection
  return array.filter((_, index) => filterMap[index]);
}

/**
 * Mostly for testing
 * @param  {Number} seconds number of seconds to sleep
 */
async function sleep(seconds, callback) {
  if (Number.isNaN(seconds)) throw new TypeError('Seconds must be a number');
  return new Promise((resolve) => {
    if (callback) {
      setTimeout(() => resolve(callback()), seconds * 1000);
    } else {
      setTimeout(resolve, seconds * 1000);
    }
  });
}

async function timeout(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

async function loopWhile(rerunAwaitable, conditionAwaitable, ms, { verbose = false } = {}) {
  /* eslint-disable no-await-in-loop */
  while (await conditionAwaitable()) {
    if (verbose) console.log('Loop While: Running Reunable Awaitable');
    await rerunAwaitable();
    if (verbose) console.log(`Loop While: Waiting ${ms} ms`);
    await timeout(ms);
  }

  if (verbose) console.log('Loop While: Finished');

  /* eslint-enable no-await-in-loop */
}

module.exports = { filterAsync, mapAsync, sleep, timeout, loopWhile };