How to create a counter app using functional components in React?

This blog describes how to create a counter app using functional components in React.

To create a counter app using functional components in React, you’ll need to maintain the state of the counter using the useState hook. For example.

CounterApp.js

import React, { useState } from 'react';

const CounterApp = () => {
  // State variable count and function setCount to update it
  const [count, setCount] = useState(0);

  // Function to increment the count
  const increment = () => {
    setCount(count + 1);
  };

  // Function to decrement the count
  const decrement = () => {
    setCount(count - 1);
  };

  return (
    <div>
      <h1>Counter App</h1>
      <p>Count: {count}</p>
      <button onClick={increment}>Increment</button>
      <button onClick={decrement}>Decrement</button>
    </div>
  );
};

export default CounterApp;

In this example:

We import React and the useState hook from ‘react’.
We define a functional component called CounterApp.
Inside the CounterApp component, we use the useState hook to create a state variable count initialized to 0, and a function setCount to update its value.
We define two functions increment and decrement to handle the increment and decrement of the count state respectively. Inside these functions, we use setCount to update the count state.
We render the count state inside a <p> element to display the current count value.
We render two buttons, one for incrementing and one for decrementing the count. We attach the increment and decrement functions to the onClick event of these buttons.

This creates a simple counter app where you can increment and decrement the count. Each time you click the buttons, the count state updates, and the component re-renders to reflect the new count value.

App.js

import React from 'react';
import ReactDOM from 'react-dom';
import CounterApp from './CounterApp';

const App = () => {
  return (
    <div>
      <CounterApp />
    </div>
  );
};

ReactDOM.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>,
  document.getElementById('root')
);

export default App;

Output

How to create a counter app using functional components in React?

Further Reading

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Further Reading

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