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What Really Happens When React State Changes?

You write this: const [ count , setCount ] = useState ( 0 ); Then the user clicks a button: setCount ( count + 1 ); And your UI changes: Count: 0 to: Count: 1 Simple, right?

  • setState() is called with new state value
  • React prepares to re-render component
  • React updates only necessary DOM parts

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