Kepiye async/await kerja?

Question

Accepted Answer

`async/await` minangka **syntax sugar over Promises** sing ngidini sampeyan nulis kode asynchronous sing maca kaya kode synchronous. Fungsi `async` tansah balik Promise; `await` ngudhakaké fungsi nganti Promise settles, banjur neruskaké kanthi nilaine.

```js
async function loadUser(id) {
  try {
    const res = await fetch(`/api/users/${id}`); // pause until the response
    const user = await res.json();               // pause until parsed
    return user;                                  // becomes the resolved value
  } catch (err) {
    console.error(err); // catches rejections from any await above
  }
}
```

## Sequential vs parallel — kesalahan performa sing umum

`await` nglakokno hal-hal **siji-siji**. Yen loro requests ora gumantung siji menyang sijine, ngewaiti dheweke kanthi urutan minangka lambat sing percaya:

```js
// ❌ sequential — total time = a + b
const a = await getA();
const b = await getB();

// ✅ parallel — total time = max(a, b)
const [a, b] = await Promise.all([getA(), getB()]);
```

## Penanganan kesalahan

Gunakake `try/catch` tinimbang `.catch`. Promise sing ditolak sing dinanteni mbuwang kesalahan, dadi siji `catch` nutupi blok kabeh.

## Sarika mesin

Masih Promises lan microtask queue — `await` ora ngalangi thread; mula kontrol supaya kode liya nglakokno, banjur neruskaké. Aja lali: nelpon fungsi `async` tanpa `await`ing (utawa `.catch`) bisa nyakup kesalahan.

## Kenapa iki penting

Gawe alur async sing ketulisan lan minangka standar modern kanggo sequence async work — nanging sampeyan kudu sadar parallelize operasi independen kanthi `Promise.all`.