Robust API Calls with Exponential Backoff and Retries

async function fetchWithRetry(url, options = {}, retries = 3, backoff = 300) {
  try {
    const response = await fetch(url, options);
    if (!response.ok) {
      // Treat non-OK responses (e.g., 5xx, 4xx) as potential retry candidates,
      // but only if it's a server error or a temporary client error (e.g., 429 Too Many Requests)
      if (response.status >= 500 || response.status === 429) {
        throw new Error(`API error: ${response.status} ${response.statusText}`);
      }
      // For other client errors (e.g., 400, 401, 403, 404), do not retry, just throw.
      // This is a common pattern, adjust based on specific API needs.
      console.error(`Non-retriable API error: ${response.status} ${response.statusText}`);
      const errorData = await response.json().catch(() => ({ message: response.statusText }));
      throw new Error(JSON.stringify({ status: response.status, data: errorData }));
    }
    return response;
  } catch (error) {
    if (retries > 0) {
      console.warn(`Retrying ${url} in ${backoff}ms due to error: ${error.message}. Retries left: ${retries - 1}`);
      await new Promise(resolve => setTimeout(resolve, backoff));
      return fetchWithRetry(url, options, retries - 1, backoff * 2); // Exponential backoff
    }
    throw error;
  }
}

// Example usage:
// fetchWithRetry('https://api.example.com/data', { method: 'GET' })
//   .then(response => response.json())
//   .then(data => console.log('Data fetched:', data))
//   .catch(error => console.error('Failed to fetch data after retries:', error.message));

// Simulate a flaky API endpoint
let attemptCount = 0;
const flakyApiUrl = 'https://httpstat.us/503'; // Will return 503 Service Unavailable

// To test a successful retry, uncomment this and comment out the above line:
// const flakyApiUrl = 'https://httpstat.us/200'; // Always succeeds
// setTimeout(() => { flakyApiUrl = 'https://httpstat.us/200'; }, 1000); // Simulate success after delay

const testFetch = async () => {
  attemptCount++;
  console.log(`Attempt ${attemptCount} for flaky API`);
  try {
    const response = await fetchWithRetry(flakyApiUrl, {}, 3, 500);
    const text = await response.text();
    console.log('Flaky API successful:', text);
  } catch (error) {
    console.error('Flaky API failed after retries:', error.message);
  }
};

// Call the test function
// testFetch();