#401 useState

easy
react

What will be the output in console for the following code when button is clicked:

import { useState, Suspense } from "react";

export default function App() {
  const [count, setCount] = useState(0);

  const updateCount = () => {
    setCount(count + 1);
    setCount(count + 2);
  }

  console.log(count);

  return (
    <button onClick={updateCount}>{count} Count</button>
  );
}

  1. On first render

    • count = 0
    • Console shows: 0
    • Button shows: 0 Count

  2. Click the button (1st time)

    • React sees two updates:

      • setCount(count + 1) → wants to set count = 1
      • setCount(count + 2) → wants to set count = 2

    • React batches updates → the last one wins (count = 2)

    • Console shows: 2

    • Button shows: 2 Count

  3. Click the button (2nd time)

    • Now count = 2

    • Updates:

      • setCount(count + 1) → count = 3
      • setCount(count + 2) → count = 4 (last one wins)

    • Console shows: 4

    • Button shows: 4 Count

Final console output sequence

0   // initial render
2   // after first click
4   // after second click
6   // after third click
... and so on