bugl
bugl
HomeLearnPatternsSearch
HomeLearnPatternsSearch

Loading lesson path

Learn/React/React Core
React•React Core

Your First React App

Now that your development environment is set up, let's try to modify the default app to display "Hello, World!".

Modify the React App

Formula

Look in the my - react - app directory, and you will find a src folder. Inside the src folder there is a file called

App.js, open it and it will look like this:

Example

This is the default content of the

App.jsx file in the src folder:

import { useState } from 'react'

Formula

import reactLogo from './assets/react.svg'

import viteLogo from '/vite.svg' import './App.css'

function App() {
const [count, setCount] = useState(0)
return (

<> <div> <a href="https://vitejs.dev" target="_blank">

<img src={viteLogo} className="logo" alt="Vite logo" />

</a> <a href="https://react.dev" target="_blank">

<img src={reactLogo} className="logo react" alt="React logo" />

</a> </div>

Formula

< h1 > Vite + React </h1 >

<div className="card">

<button onClick={() => setCount((count) => count + 1)}>
count is {count}

</button> <p>

Formula

Edit < code > src/App.jsx </code > and save to test HMR

</p> </div>

Formula

< p className ="read - the - docs">

Click on the Vite and React logos to learn more </p> </> )

}

export default App Try replacing the entire file content with the code below and save the file.

Example

Replace all the content of the

App.jsx file with the code below:

function App() {
return (
<div className="App">

Formula

< h1 > Hello World!</h1 >

</div>

);
}
export default App;

See the changes in the browser when you click Save. Notice that the changes are visible immediately after you save the file, you do not have to reload the browser!

The result:

Congratulations! You've just modified your first React application.

Previous

React Getting Started

Next

React Render HTML