X'inhu Promise u x'inhuma l-istati tiegħu?

Question

Accepted Answer

A **Promise** is an object representing a value that may not be available yet — the eventual result of an asynchronous operation. Għandu tliet istati:

- **pending** — inizjali, għad ma jkollux settlament.
- **fulfilled** — kamplut b'suċċess (għandu valur).
- **rejected** — falla (għandu raġuni/iżball).

Ogħla hu ssettla (fulfilled jew rejected) hu **immutable** — ma jistax jinbidel tul.

```js
fetch("/api/user")
  .then(res => res.json())     // runs on fulfillment; return value flows down
  .then(user => render(user))
  .catch(err => showError(err)) // runs on ANY rejection in the chain
  .finally(() => hideSpinner()); // always runs
```

## Chaining flatten nested async

Irritorn promise ġewwa `.then` jistenna għalih qabel jikkontiwa, għalhekk tivita callback nested profond ("callback hell"):

```js
getUser(id)
  .then(user => getPosts(user.id)) // returns a promise → chain waits for it
  .then(posts => console.log(posts));
```

## Combinators għal promise multipli

```js
Promise.all([a, b, c]);     // wait for ALL; rejects fast if any fails
Promise.allSettled([a, b]); // wait for all, get each result/error
Promise.race([a, b]);       // settles with the FIRST to settle
Promise.any([a, b]);        // first to FULFILL (ignores rejections)
```

## Għaliex hu importanti

Promises huma l-funzjoni ta' async JS — huma sostitwew callback nesting, jagħtu tqabbil ta' iżballu unifikat permezz ta' `.catch`, u `async/await` huwa biss syntax aħjar fuqu.

Nisja `.catch` (unhandled rejection) hu bug komuni.