In the nested loops I have async await. For me it is important that on each iteration loop will wait until await will be finished/data received and the start next iteration.

const _sampleFilters = async (
  pageName,
  details,
  available,
) => {
  for (const filterName of Object.keys(details)) {
    for (const filterValue of Object.keys(details[filterName])) {
      const data = (await fetchDetails(
        pageName
      ));

      details[filterName][filterValue].allDetails = cloneDeep(
        getProcessedData(
          data.map(data => data.value),
          available,
          pageName,
        ),
      );
    }
  }
};