Robust API Fetch with Exponential Backoff and Retry

async function fetchWithRetry(url, options = {}, retries = 3, backoff = 300) {
    try {
        const response = await fetch(url, options);
        if (!response.ok) {
            // Check for server errors (5xx) or transient client errors (429 Too Many Requests)
            // that might be worth retrying. For 400s or 401s, retry is usually not helpful.
            if (response.status >= 500 || response.status === 429) {
                throw new Error(`API error: ${response.status} ${response.statusText}`);
            }
            // For other client errors, don't retry, just throw.
            throw new Error(`Client error: ${response.status} ${response.statusText}`);
        }
        return await response.json();
    } catch (error) {
        if (retries > 0) {
            console.warn(`Retrying API call to ${url} in ${backoff}ms. Retries left: ${retries - 1}`);
            await new Promise(resolve => setTimeout(resolve, backoff));
            return fetchWithRetry(url, options, retries - 1, backoff * 2); // Exponential backoff
        }
        throw error; // No retries left, rethrow the error
    }
}

// Usage Example:
/*
(async () => {
    try {
        const data = await fetchWithRetry('https://jsonplaceholder.typicode.com/posts/1', { method: 'GET' });
        console.log('Fetched data:', data);

        // Example of a failing call (simulate 500 error)
        // const failingData = await fetchWithRetry('https://httpstat.us/500', { method: 'GET' }, 2);
        // console.log('Failing data (should not reach here):', failingData);
    } catch (err) {
        console.error('Failed to fetch after multiple retries:', err.message);
    }
})();
*/