Menene memoization kuma ta yaya za ka aiwatar da shi?

Question

Accepted Answer

**Memoization** yana ajiya sakamakon aiki ta hanyar kwatance da jajagalinsa, saboda kira bugi-bugi tare da abubuwan shigarwa iri daya zasu mayar da sakamakon ajiyawa nan da nan maimakon sake ƙididdige. Yana cimma **ƙarfin ajiya don saurin" kuma yana aiki ne kawai tare da ayyukan **tsarewa** (abubuwan shigarwa iri daya → bukatu iri daya, babu tasirin gida).

## Kwatayo memoize na addini

```js
function memoize(fn) {
  const cache = new Map();
  return (...args) => {
    const key = JSON.stringify(args); // build a cache key from the arguments
    if (cache.has(key)) {
      return cache.get(key);          // cache hit — skip the work
    }
    const result = fn(...args);
    cache.set(key, result);
    return result;
  };
}

const slowSquare = n => { /* expensive */ return n * n; };
const fastSquare = memoize(slowSquare);
fastSquare(4); // computes → 16
fastSquare(4); // cached → 16 instantly
```

## Nasara ta gida: Fibonacci mai sake dawowa

```js
const fib = memoize(n => (n < 2 ? n : fib(n - 1) + fib(n - 2)));
// turns exponential O(2^n) into roughly O(n) by caching subproblems
```

## Musayar da juna da gargajiya

- **Dabarun sarari maɓalli**: `JSON.stringify` yana kasa tare da ayyuka, kuma odar maɓalli tana da mahimmanci ga abubuwan. Don jajagalinsa na abubuwan, `WeakMap` (maɓallina ta hanyar tunani) yana jiyewa ajiyawa ɗin iska.
- **Girma marasa iyaka**: ajiya ɗin bai kuncewa ba - yi amfani da ajiya ta **LRU** don jajagalinsa mai dogon lokaci.
- Yi memoize ne kawai lokacin da sake ƙididdige ya kasance mai tsada da gaske kuma abubuwan shigarwa suna maimaitawa.

## Me ya sa haka makamancin

Memoization iko a cikin gida: React's `useMemo`/`React.memo`, Reselect masu zaɓa, lissafi na yau da kullun.

Kaɗi (ajiya sakamakon tsarewa ta hanyar shigarwa) daidai yake; sana'a shine zaɓa maɓalli da kutsewa ajiya.