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Components & JSX interview questions

18 real Components & JSX questions from the React bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is JSX?

Junior
  1. A.a syntax extension that compiles to React.createElement calls describing the UI
  2. B.read-only inputs passed from a parent component down to a child
  3. C.a stable identity React uses to match list items across renders for efficient reconciliation
  4. D.a <>...</> wrapper that groups children without adding an extra DOM node
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3. Which statement is correct?

Junior
  1. A.JSX — a function that returns JSX for React to render and receives props as its input
  2. B.JSX — a form input whose value is driven by React state rather than by the DOM
  3. C.JSX — a syntax extension that compiles to React.createElement calls describing the UI
  4. D.JSX — a stable identity React uses to match list items across renders for efficient reconciliation
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4. What is Component?

Junior
  1. A.a <>...</> wrapper that groups children without adding an extra DOM node
  2. B.a function that returns JSX for React to render and receives props as its input
  3. C.a syntax extension that compiles to React.createElement calls describing the UI
  4. D.a stable identity React uses to match list items across renders for efficient reconciliation
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6. Which statement is correct?

Junior
  1. A.Component — a form input whose value is driven by React state rather than by the DOM
  2. B.Component — a syntax extension that compiles to React.createElement calls describing the UI
  3. C.Component — a <>...</> wrapper that groups children without adding an extra DOM node
  4. D.Component — a function that returns JSX for React to render and receives props as its input
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7. What is Props?

Junior
  1. A.read-only inputs passed from a parent component down to a child
  2. B.a form input whose value is driven by React state rather than by the DOM
  3. C.a syntax extension that compiles to React.createElement calls describing the UI
  4. D.a <>...</> wrapper that groups children without adding an extra DOM node
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9. Which statement is correct?

Junior
  1. A.Props — a syntax extension that compiles to React.createElement calls describing the UI
  2. B.Props — a <>...</> wrapper that groups children without adding an extra DOM node
  3. C.Props — a stable identity React uses to match list items across renders for efficient reconciliation
  4. D.Props — read-only inputs passed from a parent component down to a child
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10. What is key prop?

Mid
  1. A.a syntax extension that compiles to React.createElement calls describing the UI
  2. B.a <>...</> wrapper that groups children without adding an extra DOM node
  3. C.a function that returns JSX for React to render and receives props as its input
  4. D.a stable identity React uses to match list items across renders for efficient reconciliation
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12. Which statement is correct?

Mid
  1. A.key prop — a stable identity React uses to match list items across renders for efficient reconciliation
  2. B.key prop — a function that returns JSX for React to render and receives props as its input
  3. C.key prop — a form input whose value is driven by React state rather than by the DOM
  4. D.key prop — read-only inputs passed from a parent component down to a child
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13. What is Fragment?

Junior
  1. A.a function that returns JSX for React to render and receives props as its input
  2. B.a syntax extension that compiles to React.createElement calls describing the UI
  3. C.a <>...</> wrapper that groups children without adding an extra DOM node
  4. D.a stable identity React uses to match list items across renders for efficient reconciliation
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15. Which statement is correct?

Junior
  1. A.Fragment — a <>...</> wrapper that groups children without adding an extra DOM node
  2. B.Fragment — read-only inputs passed from a parent component down to a child
  3. C.Fragment — a syntax extension that compiles to React.createElement calls describing the UI
  4. D.Fragment — a function that returns JSX for React to render and receives props as its input
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16. What is Controlled component?

Mid
  1. A.read-only inputs passed from a parent component down to a child
  2. B.a form input whose value is driven by React state rather than by the DOM
  3. C.a syntax extension that compiles to React.createElement calls describing the UI
  4. D.a <>...</> wrapper that groups children without adding an extra DOM node
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18. Which statement is correct?

Mid
  1. A.Controlled component — a stable identity React uses to match list items across renders for efficient reconciliation
  2. B.Controlled component — a form input whose value is driven by React state rather than by the DOM
  3. C.Controlled component — a function that returns JSX for React to render and receives props as its input
  4. D.Controlled component — a <>...</> wrapper that groups children without adding an extra DOM node
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