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What are React's design principles?

Q: What are React's design principles?

**Core concept (TL;DR).** React's guiding ideas: be **declarative**, **component-based**, favour **composition over inheritance**, enforce **one-way data flow**, keep rendering **pure**, and prioritize **gradual adoption** and developer experience ("learn once, write anywhere"). These principles explain most of React's APIs. The ideas behind the API declarative · component-based <rect x="20" y="74" width="232" height="24" rx="5" fill="#8b5cf6" fill

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This question aims to understand if the candidate grasps the core philosophy behind React.

design principlesdeclarativecomponentsarchitecture

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Composition over inheritance, in practice

// React reuses behaviour by COMPOSING, not subclassing.
function Panel({ title, children }) {       // generic, declarative
  return (
    <section style={{ border: "1px solid #ccc", padding: 12, borderRadius: 8 }}>
      <strong>{title}</strong>
      {children}                              {/* composition */}
    </section>
  );
}

export default function App() {
  return (
    <div style={{ padding: 24, fontFamily: "system-ui" }}>
      <Panel title="Profile"><p>Composed, not inherited.</p></Panel>
    </div>
  );
}

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