A_TestDriveResponse.json

{
  "promo": "NTDAW",
  "restriction": {
    "type": "DATE",
    "start": "...",
    "end": "...",
    "tz": "America/Los_Angeles"
  }
}

B_getPromo.ts

enum PromoValues {
  NONE,
}

enum RestrictionType {
  DATE,
}

async function getPaymentSpeedDefinitions(context) {
  let promoType = PROMO_TYPE.NONE;
  if (await tdClient.isSwitchOn(PROMOTIONS)) {
    promoType = await getPromoType(context);
  }
  return await context.dao.paymentSpeed.findAllPOaymentSpeedDefinitions(promoType);
}

async function getPromoType(context): PromoType {
  const flagResult = await tdclient.getFlag(flag_name, { carrierId: context.carrierId })
  const promoDetails = flagResult.jsonValues();

  if (!promoDetails) {
    return PromoValues.NONE;
  }

  const { restriction, promoType } = promoDetails;
  switch (restriction.type as RestrictionType) {
    case RestrictionType.DATE:
      return getDateRestrictionType(promoDetails);
    case DEFAULT:
      console.error('unsupported promo type', { context } );
      return PromoValues.NONE;
  }
}

function getDateRestrictionType({ restriction: { start, end, tz }, promoType }) {
  const now = moment.tz(tz);
  const start = moment.tz(tz, start);
  const end = moment.tz(tz, end);

  if (now.between(start, end)) {
    return promoType;
  }

  return PromoValues.NONE;
}