Flash cards
Review the key moves
What is the main idea behind Upgrade React?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ i react@latest react-dom@latestPut the learning moves in the order that makes the concept easiest to apply.
Upgrade to React 19
Upgrading an existing React application to version 19 only requires two steps.
If you are already using the latest version of React, you can skip this section.
Step 1: Install React 19
To install the latest version, from your project folder run the following from the terminal:
npm i react@latest react-dom@latestStep 2: Use the new root API
In order to take advantage of React 19's concurrent features you'll need to use the new root API for client rendering.
// Before import ReactDOM from 'react-dom';
ReactDOM.render( <h1>Hello React!</h1>, document.getElementById('root') );
// After import { createRoot } from 'react-dom/client';
createRoot(document.getElementById('root')).render( <h1>Hello React!</h1> );Your application will work without using the new root API. If you continue to use ReactDOM.render your application will behave like React 17.