1. Resilient Promise Retry with Exponential Backoff & Jitter

Test this production-grade network resilience function directly in the editor:

async function fetchWithRetry(fn, retries = 3, delay = 500, backoff = 2) {
  try {
    return await fn();
  } catch (error) {
    if (retries <= 0) throw error;
    
    // Calculate exponential delay with randomized jitter
    const jitter = Math.random() * 200;
    const waitTime = delay + jitter;
    
    console.warn(`Attempt failed: "${error.message}". Retrying in ${Math.round(waitTime)}ms (${retries} attempts left)...`);
    await new Promise(resolve => setTimeout(resolve, waitTime));
    
    return fetchWithRetry(fn, retries - 1, delay * backoff, backoff);
  }
}

// Example usage in the sandbox:
let attempt = 0;
const simulateApi = () => new Promise((resolve, reject) => {
  attempt++;
  if (attempt < 3) reject(new Error('503 Service Unavailable'));
  else resolve({ status: 200, payload: 'Operation Successful!' });
});

fetchWithRetry(simulateApi)
  .then(res => console.log('Final Result:', res))
  .catch(err => console.error('Failed completely:', err));

2. Deep Object Serialization via native structuredClone

const complexState = {
  id: 101,
  date: new Date(),
  regex: /^[a-z]+$/i,
  metadata: new Map([['tier', 'enterprise'], ['active', true]]),
  items: [1, 2, 3]
};

// structuredClone handles cyclic references, Maps, Sets, and Dates natively
const deepCopy = structuredClone(complexState);
deepCopy.items.push(4);

console.log('Original items length:', complexState.items.length); // 3
console.log('Cloned items length:', deepCopy.items.length);     // 4