Promise.all(), Promise.race(), and Promise.any()

What optimization pattern is demonstrated here?

const cache = new Map();
async function fetchWithCache(urls) {
  const promises = urls.map(url => {
    if (cache.has(url)) return cache.get(url);
    const promise = fetch(url).then(r => r.json());
    cache.set(url, promise);
    return promise;
  });
  return Promise.all(promises);
}

Request batching
Promise memoization
This implements promise memoization: 1) Caches promise objects, not just results, 2) Prevents duplicate requests for same URL, 3) Returns same promise for concurrent requests, 4) Maintains promise state across calls, 5) Efficient for handling parallel requests to same URLs, 6) Common pattern in API client implementations.
Error handling
Load balancing

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