# Form & Controlled Components (React / Next.js)

> Controlled components, uncontrolled components, validasi form, React Hook Form, penanganan submit

- 20 pertanyaan wawancara
- Mid-Level
- [Pertanyaan Wawancara: React / Next.js](https://sharpskill.dev/id/technologies/react-next/pertanyaan-wawancara.md)

## 1. Apa itu controlled component di React?

**Jawaban**

Controlled component adalah elemen form yang nilainya dikelola oleh state React melalui prop value dan handler onChange. Ini berarti React menjadi satu-satunya sumber kebenaran untuk data tersebut. Berbeda dengan uncontrolled components di mana DOM mempertahankan nilainya sendiri, controlled components memberikan kontrol penuh atas data form dan memudahkan validasi secara real-time.

## 2. Bagaimana cara membuat controlled input di React?

**Jawaban**

Controlled input membutuhkan dua elemen penting: prop value yang terikat pada state React dan handler onChange untuk memperbarui state tersebut. Tanpa onChange, input akan menjadi read-only karena React akan mencegah modifikasi apa pun. Pendekatan ini memastikan state React tetap sinkron dengan nilai input yang ditampilkan, memungkinkan validasi langsung atau transformasi data.

## 3. Apa perbedaan antara controlled component dan uncontrolled component?

**Jawaban**

Perbedaan mendasar terletak pada sumber kebenaran data. Controlled component menyimpan nilainya di state React (satu-satunya sumber kebenaran), sementara uncontrolled component membiarkan DOM mengelola nilainya sendiri, yang dapat diakses melalui ref. Controlled components menawarkan lebih banyak kontrol dan memudahkan validasi real-time, tetapi uncontrolled components bisa lebih sederhana untuk form dasar tanpa validasi kompleks.

## 17 pertanyaan lagi tersedia

- Bagaimana cara mengelola beberapa controlled input dalam satu form?
- Bagaimana cara membuat controlled checkbox di React?

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