What are controlled and uncontrolled components in React?

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Controlled Components

• In a controlled component, form data is handled by React state.

• The input field’s value is always driven by state, and any change updates the state via an event handler.

• React has full control over the data, making it easier to validate, reset, or manipulate input values.

• Example: A text input where value={stateValue} and onChange={handleChange} keep the state and UI in sync.

• Use case: When you need validation, conditional rendering, or dynamic form updates.

Uncontrolled Components

• In an uncontrolled component, form data is handled by the DOM itself rather than React state.

• You use ref to directly access the input’s current value when needed.

• React does not continuously track the input’s value, which makes it simpler but less flexible.

• Example: <input type="text" ref={inputRef} /> where you read the value only when submitting.

• Use case: When you need quick forms without heavy validation or state management.

Key Difference in a Line

• Controlled Component: React controls the input (state-driven).

• Uncontrolled Component: The DOM controls the input (ref-driven).

⚡ Interview Tip: Controlled components give more power and consistency, while uncontrolled ones are lightweight and sometimes faster to implement.

Read More :

Explain the concept of Virtual DOM in React.

What is the difference between useEffect() and useLayoutEffect()?

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