Error Reference

async function fetchWithRetry(url, options, maxRetries = 4) {
  const retryableStatuses = new Set([429, 503]);

  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    const response = await fetch(url, options);

    if (!retryableStatuses.has(response.status)) {
      // Success, or a non-retryable error — return immediately
      return response;
    }

    if (attempt === maxRetries) {
      // We have exhausted our retries
      return response;
    }

    // Exponential backoff: 1s, 2s, 4s, 8s
    const backoffMs = Math.pow(2, attempt) * 1000;
    // Add up to 500ms of random jitter to avoid thundering herd
    const jitterMs = Math.random() * 500;
    const waitMs = backoffMs + jitterMs;

    console.warn(
      `Request failed with ${response.status}. Retrying in ${Math.round(waitMs)}ms ` +
      `(attempt ${attempt + 1} of ${maxRetries})...`
    );

    await new Promise(resolve => setTimeout(resolve, waitMs));
  }
}

// Usage
const response = await fetchWithRetry(
  'https://sandbox.api.unionbank.ng/api/v1/accounts',
  {
    headers: {
      'Authorization': `ApiKey ${process.env.UBN_API_KEY}`,
      'Content-Type': 'application/json',
    },
  }
);