What are React controlled components and uncontrolled components?

A Controlled Component takes its current value through props and notifies changes through callbacks like onChange. A parent component "controls" it by handling the callback and managing its own state and passing the new values as props to the controlled component. This is also called "dumb component".

A Uncontrolled Component stores its own state internally, and you query the DOM using a ref to find its current value when you need it. This is a bit more like traditional HTML.

// Controlled:
<input type="text" value={value} onChange={handleChange} />

// Uncontrolled:
<input type="text" defaultValue="foo" ref={inputRef} />
// Use `inputRef.current.value` to read the current value of <input>

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