Upgrade to React 18
Upgrading an existing React application to version 18 only requires two steps.
Note- If you are already using the latest version of create-react-app which uses React version 18 you can skip this section.
Step 1: Install React 18
To install the latest version, from your project folder run the following from the terminal:
npm i react@latest react-dom@latest
Step 2: Use the new root API
In order to take advantage of React 18's concurrent features you'll need to use the new root API for client rendering.
// Before
import ReactDOM from 'react-dom';
ReactDOM.render(<App />, document.getElementById('root'));
// After
import ReactDOM from 'react-dom/client';
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);
Your application will work without using the new root API. If you continue to use ReactDOM.render your application will behave like React 17.