Piye beda antara panah fungsi karo fungsi biasa?

Question

IT Interview Practice · Accepted Answer

Arrow functions luwih ringkes, nanging prabédan nyata ana ing **perilaku ikatan**, ora mung sintaks.

```js
const regular = function () {};
const arrow = () => {};
const short = x => x * 2; // implicit return for one expression
```

## Beda utamané

**1. Ora duwe `this` dhewe** — panah tumurun `this` saka cakupan sing nunutup. Iki beda paling penting lan kenapa padha apik banget kanggo callback:

```js
const timer = {
  seconds: 0,
  start() {
    setInterval(() => this.seconds++, 1000); // ✅ `this` is timer
    // a regular function here would have its own `this` (undefined) → bug
  },
};
```

**2. Ora duwe obyek `arguments`** — gunakake rest parameters kebak:

```js
const sum = (...args) => args.reduce((a, b) => a + b, 0);
```

**3. Ora bisa digunakake minangka konstruktor** — `new arrow()` ngomong, lan ora duwe `prototype`.

## Yen BOTEN nggunakake panah

```js
const obj = {
  name: "Ann",
  greet: () => `Hi ${this.name}`, // ❌ `this` is NOT obj (it's outer scope)
  greet2() { return `Hi ${this.name}`; }, // ✅ method needs dynamic `this`
};
```

Jangan gunakake panah kanggo **metode obyek** (ora bakal ikatan ing obyek) utawa yen butuh `this` dinamis/`arguments` (pamidhandel acara sing ngandelake `this` minangka elemen).

## Kenapa iku penting

Gunakake panah kanggo callback lan fungsi pendek ing ngendi tumurun `this` iku apa sing dikarepake; gunakake fungsi biasa kanggo metode, konstruktor, lan metode prototyp.

Beda utamané

Yen BOTEN nggunakake panah

Kenapa iku penting

Pitakon sing gegandhengan