New feature in react 18

React 18 is a significant update to the popular JavaScript library for building user interfaces. It introduces several new features and improvements aimed at enhancing performance and developer experience. Here are some of the key updates in React 18:

1. Concurrent Rendering

React 18 introduces concurrent rendering, that is to prepare multiple versions of the UI simultaneously. This feature gives the app's responsiveness and allows it to handle large amounts of data more efficiently. React can work on different parts of the UI in parallel and pause when more important updates, like user interactions, are needed.

2. Automatic Batching

In React 18, updates are automatically batched, that is multiple state updates are grouped together and rendered at the same time. This reduces the number of renders and improves performance. Previously, React only batched updates inside event handlers. Now, this behavior is extended to all updates, including those inside asynchronous code.

3. New Root API

React 18 introduces a new createRoot API for rendering React applications. This replaces the older ReactDOM.render method and is designed to enable concurrent rendering features. The new API provides a more consistent and flexible way to manage rendering in your application.

Example:

import { createRoot } from 'react-dom/client';
const root = createRoot(document.getElementById('root'));
root.render(<App />);

4. Transitions

React 18 introduces a concept called "transitions," which help differentiate between important and non-important updates. This helps maintain a smooth user experience by prioritizing urgent updates.

import { useTransition } from 'react';
const [isPending, startTransition] = useTransition();
startTransition(() => {
 // Non-urgent state update
 setState(newState);
});

5. Suspense Improvements

React 18 enhances the Suspense component, which allows developers to handle asynchronous data more effectively. The new improvements make it easier to manage loading states and error handling in React applications. Suspense now works seamlessly with server-side rendering (SSR) and concurrent rendering features.

6. Streaming Server-Side Rendering (SSR)

React 18 introduces improvements to server-side rendering, especially streaming SSR. Improving the time to first byte (TTFB) hence overall performance is improved. It allows certain parts of the UI to render more quickly while other parts are still loading.
 

7. Concurrent Features for Developers

React 18 introduces several concurrent features that developers can opt into. These features help improve the performance and responsiveness of React applications by allowing developers to control how updates are prioritized and processed.

8. Improved Strict Mode

Strict Mode in React 18 has been improved, so that It will show extra checks and warnings to assist developers in detecting and resolving issues early in the development phase.

9. New Hooks and API Changes

React 18 includes several new hooks and changes to existing APIs to support concurrent rendering and other new features. For example, useSyncExternalStore and useInsertionEffect are new hooks introduced in this version.