Implement memoize() with custom resolver and cache limit

Question

Accepted Answer

**Approach:** Map cache keyed by resolver or JSON.stringify. On hit return cached; on miss compute, set, and evict if over maxSize. Expose `cache` Map.

```javascript
function memoize(func, resolver, maxSize = Infinity) {
  const cache = new Map();
  function memoized(...args) {
    const key = resolver ? resolver(...args) : JSON.stringify(args);
    if (cache.has(key)) return cache.get(key);
    const result = func.apply(this, args);
    if (cache.size >= maxSize) {
      const firstKey = cache.keys().next().value;
      cache.delete(firstKey);
    }
    cache.set(key, result);
    return result;
  }
  memoized.cache = cache;
  memoized.clear = () => cache.clear();
  return memoized;
}

// Demo
const add = memoize((a,b) => { console.log('compute', a,b); return a+b; });
console.log(add(1,2)); // compute 1 2 -> 3
console.log(add(1,2)); // cached 3 (no log)
console.log(add(2,3)); // compute 2 3 -> 5
const fetchUser = memoize((id, opts) => ({id}), (id) => String(id));
console.log(fetchUse

Implement memoize() with custom resolver and cache limit

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STREAK ALIVE.

Understand the problem

Attempt it yourself

Study the solution

Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.