React Essentials · Props & State · Lesson 5 of 26

useState Basics

Concept

useState Basics

useState gives a component its own memory that persists between renders and triggers a re-render when updated.

By the end of this lesson

Explain the core idea behind useState Basics.
Predict output before running a change.
Test one realistic and one unusual input.
Use the result to make the next decision.

How to study this page

1. Read one concept.
2. Change the example.
3. Run, compare, and explain.
4. Complete the challenge below.

ExampleRunnable

import { useState } from "react";

function Counter() {
  const [count, setCount] = useState(0);
  return <button onClick={() => setCount(count + 1)}>{count}</button>;
}

Try it Yourself »

Self-check before continuing

Without looking at the example, describe what changes when you modify one input in useState Basics. Then reopen the editor and prove your explanation with a small test.

You are ready to continue when you can predict, test, and explain the result.

Your turn

Build a counter that also has a Reset button.

Loading editor…

Console

Output will appear here...