Robust API Fetch with Exponential Backoff

/**
 * Fetches data from an API with exponential backoff and retries.
 * @param {string} url - The API endpoint URL.
 * @param {object} options - Fetch options (method, headers, body, etc.).
 * @param {number} retries - Maximum number of retries.
 * @param {number} delay - Initial delay in milliseconds for retries.
 * @returns {Promise<Response>} The fetch response.
 * @throws {Error} If all retries fail.
 */
async function fetchDataWithRetries(url, options = {}, retries = 3, delay = 1000) {
    let attempt = 0;
    while (attempt < retries) {
        try {
            const response = await fetch(url, options);
            if (!response.ok) {
                // If response is not OK, but not a network error, it's still a "failure" for this retry logic
                // Could check for specific status codes like 429 (Too Many Requests) or 5xx
                // For simplicity, we'll re-throw for any non-ok response here
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            return response;
        } catch (error) {
            attempt++;
            console.error(`Attempt ${attempt} failed: ${error.message}`);
            if (attempt < retries) {
                const backoffDelay = delay * Math.pow(2, attempt - 1);
                console.log(`Retrying in ${backoffDelay}ms...`);
                await new Promise(resolve => setTimeout(resolve, backoffDelay));
            } else {
                throw new Error(`Failed to fetch ${url} after ${retries} attempts: ${error.message}`);
            }
        }
    }
}

// Example usage:
// (async () => {
//     try {
//         const data = await fetchDataWithRetries('https://api.example.com/data', {
//             method: 'GET',
//             headers: { 'Content-Type': 'application/json' }
//         }, 5, 500); // 5 retries, starting with 500ms delay
//         const json = await data.json();
//         console.log('Fetched data:', json);
//     } catch (error) {
//         console.error('Final fetch error:', error.message);
//     }
// })();