Callbacks & Callback Hell

What callback optimization technique is shown here?

const cache = new Map();
function memoize(fn) {
  return function(arg, callback) {
    const cached = cache.get(arg);
    if (cached) {
      return process.nextTick(() => callback(null, cached));
    }
    fn(arg, (err, result) => {
      if (!err) cache.set(arg, result);
      callback(err, result);
    });
  };
}

Debouncing
Throttling
Memoization
This code implements memoization for callback-based functions. Key features: 1) Caches results of expensive async operations, 2) Uses process.nextTick to maintain async behavior even for cached results, 3) Properly handles and propagates errors, 4) Implements the error-first callback pattern, 5) Only caches successful results. This optimization is particularly useful for expensive async operations with repeated identical inputs.
Batching

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