Robust API Call Retries with Exponential Backoff

async function fetchDataWithRetry(url, options = {}, retries = 3, delay = 1000) {
  try {
    const response = await fetch(url, options);
    if (response.ok) {
      return await response.json();
    } else if (response.status === 429 || response.status >= 500 && retries > 0) {
      console.warn(`Attempt failed for ${url}. Retrying in ${delay / 1000}s... (Retries left: ${retries})`);
      await new Promise(resolve => setTimeout(resolve, delay));
      return fetchDataWithRetry(url, options, retries - 1, delay * 2); // Exponential backoff
    } else {
      const errorData = await response.json().catch(() => ({ message: response.statusText }));
      throw new Error(`API error: ${response.status} - ${errorData.message || response.statusText}`);
    }
  } catch (error) {
    if (retries > 0) {
      console.warn(`Network error for ${url}. Retrying in ${delay / 1000}s... (Retries left: ${retries})`);
      await new Promise(resolve => setTimeout(resolve, delay));
      return fetchDataWithRetry(url, options, retries - 1, delay * 2); // Exponential backoff
    } else {
      console.error(`Max retries exceeded for ${url}:`, error);
      throw error;
    }
  }
}

// Example usage:
(async () => {
  try {
    const data = await fetchDataWithRetry('https://api.example.com/data-that-might-fail', {}, 5);
    console.log('Successfully fetched data:', data);
  } catch (error) {
    console.error('Failed to fetch data after multiple retries:', error.message);
  }
})();

// Example usage with a mock failing API
let requestCount = 0;
async function mockFailingApi(url) {
    requestCount++;
    if (requestCount < 3) {
        console.log(`Mock API call ${requestCount}: Failing with 500`);
        return new Response(JSON.stringify({ message: 'Internal Server Error' }), { status: 500 });
    } else {
        console.log(`Mock API call ${requestCount}: Succeeding`);
        return new Response(JSON.stringify({ message: 'Success after retries', data: [1,2,3] }), { status: 200 });
    }
}

// Replace global fetch for demonstration purposes (do not do this in production)
// const originalFetch = global.fetch;
// global.fetch = mockFailingApi;

// (async () => {
//   try {
//     requestCount = 0; // Reset for this example
//     const data = await fetchDataWithRetry('https://mock-api.example.com/sometimes-fails', {}, 3);
//     console.log('Mock API - Successfully fetched data:', data);
//   } catch (error) {
//     console.error('Mock API - Failed after multiple retries:', error.message);
//   } finally {
//     global.fetch = originalFetch; // Restore original fetch
//   }
// })();