Apa utilitas sing membantu ngerjakan kode async (promisify, AbortController)?

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Accepted Answer

Node nyedhiyakake sawetara utilitas sing nggawe kode async luwih resik lan luwih bisa dikontrol — ngganti API callback lawas menyang Promises, mbatalake operasi, lan koordinasi tugas async sing pirang-pirang.

## promisify — ngganti API callback menyang Promises

```js
import { promisify } from "util";
import fs from "fs";

// turn an error-first callback function into a Promise-returning one
const readFileAsync = promisify(fs.readFile);
const data = await readFileAsync("file.txt", "utf8"); // now awaitable
```

`promisify` mbalut sembarang fungsi callback standar `(args..., (err, result) => {})` supaya bisa `await` — migunani kanggo pustaka luwih lawas sing durung duwe Promises. (Akeh built-ins sing saiki nawakake versi promise kanthi langsung, contone `fs/promises`.)

## AbortController — batalake operasi async

```js
const controller = new AbortController();

// pass the signal to a cancellable operation
const promise = fetch("https://api.example.com", { signal: controller.signal });

// cancel it (e.g. on timeout or user navigation)
setTimeout(() => controller.abort(), 5000); // abort after 5s

try {
  await promise;
} catch (err) {
  if (err.name === "AbortError") console.log("request cancelled");
}
```

`AbortController` nyedhiyakake cara standar kanggo **membatalake** operasi ing-flight (fetch, timers, streams, akeh pustaka) — penting kanggo timeouts lan nglirwakake kerja sing terbuang-buang nalika hasil ora perlu maneh.

## Promise combinators — koordinasi tugas async pirang-pirang

```js
// run in parallel, wait for ALL (fails fast if any rejects)
const [a, b, c] = await Promise.all([getA(), getB(), getC()]);

// wait for all, get each result OR error (never short-circuits)
const results = await Promise.allSettled([getA(), getB()]);

// the first to settle (resolve OR reject) wins
const fastest = await Promise.race([fetchPrimary(), fetchBackup()]);

// the first to FULFILL (ignores rejections until one succeeds)
const first = await Promise.any([source1(), source2()]);
```

Combinators iki ngandharake pola umum: `all` kanggo parallel-lan-nganteni, `allSettled` nalika sampeyan butuh saben asil ajeg-ajeg saka gagal, `race` kanggo timeouts/paling-cepet-menang, `any` kanggo sumber fallback.

## setTimeout minangka Promise (modern)

```js
import { setTimeout as sleep } from "timers/promises";
await sleep(1000); // await a delay without wrapping in a Promise manually
```

## Apa gunane

Utilitas iki nggawe kode async Node nyata luwih resik lan luwih kuwat: `promisify` nggembung API callback lawas menyang async/await, `AbortController` nambah pembatalan lan timeouts (nyegeg operasi sing nggantung utawa terbuang-buang), lan Promise combinators (`all`/`allSettled`/`race`/`any`) ngandharake pola koordinasi umum kanthi singkat lan bener.

Ngerti marang wong-wong mau ndadekake sampeyan bisa nangani paralelisme, pembatalan, lan fallback kanthi elegan tinimbang ngarang maneh — butuh umum ing aplikasi async sembarang sing ora trivial.