X'inhuma iterators u generators?

Question

Accepted Answer

An **iterator** huwa oġġett b'metodu `next()` li jirritorna `{ value, done }`. Oġġett huwa **iterable** jekk ikollu metodu `[Symbol.iterator]` — dak li jagħmilha `for...of` u spread jaħdmu. A **generator** (`function*`) huwa mod konvenjenti biex toħloq iterators li jistgħu **jitwaqqfu u jibdew mill-ġdid** b'`yield`.

## Generators jipproduċu valuri b'mod late-binding

```js
function* idGenerator() {
  let id = 1;
  while (true) {     // infinite, but lazy — only computes on demand
    yield id++;      // pause here, return a value, resume on next()
  }
}
const gen = idGenerator();
gen.next().value; // 1
gen.next().value; // 2 — execution resumed where it paused
```

L-idea ewlenija: l-esekuzzjoni **toqqof** f'kull `yield` u **tibda mill-ġdid** fuq in-next `.next()`, preserving l-istat lokali bejn it-tluq. M'hemmx ħaġa li tiġi kkalkulata sakemm ma titlobx.

## Għaliex il-late-binding hi importanti

```js
// process a huge/infinite sequence without building it all in memory
function* take(iterable, n) {
  let i = 0;
  for (const x of iterable) {
    if (i++ >= n) return;
    yield x;
  }
}
[...take(idGenerator(), 3)]; // [1, 2, 3] — from an infinite generator
```

## Għixieraq iterable customizzat

```js
const range = {
  from: 1, to: 3,
  *[Symbol.iterator]() { for (let i = this.from; i <= this.to; i++) yield i; },
};
[...range]; // [1, 2, 3] — works with for...of and spread
```

## Għaliex dak importanti

Generators jippermetti sequenzi late/infiniti, iterazzjoni customizzata, u streaming effiċjenti fil-memoria.

Huma kienu wkoll il-bazi ta' libreriji async bikrija (co) u jinsabu taħt il-iterazzjoni async (`for await...of`).

Il-protokoll iterator huwa dak li jagħmilha `for...of`, spread, u destructuring united madwar arrays, Maps, Sets, u strings.