Last updated on August 28th, 2024
Today, we will explore the newly released stable version of React 18. In this session, we’ll highlight the key changes and improvements introduced in this latest update.
React 18 places a strong emphasis on enhancing UI performance through a range of new features and improvements enabled by “concurrent rendering.” This update is designed to deliver smoother and more responsive user experiences while introducing only minimal breaking changes.
Let’s take a look at the major updates of React18:
Root API
With the introduction of React 18, the Root API brings a new method called `ReactDOM.createRoot`. Previously, developers used `ReactDOM.render` to mount components to the DOM. Moving forward, `ReactDOM.createRoot` will be the standard approach for creating a root and subsequently passing it to the render function.
The good news is that existing code using `ReactDOM.render` will continue to function correctly for now. However, it’s advisable to begin the transition to `createRoot`, as `render` is set to be deprecated in future releases of React 18. The legacy `ReactDOM.render` is still available to help facilitate this transition.
React 17:
“`javascript
import React from ‘react’;
import ReactDOM from ‘react-dom’;
const App = () => {
return <h1>Hello World!</h1>;
};
ReactDOM.render(<App />, document.getElementById(‘root’));
“`
React 18:
“`javascript
import React from ‘react’;
import ReactDOM from ‘react-dom’;
const App = () => {
return <h1>Hello World!</h1>;
};
const root = ReactDOM.createRoot(document.getElementById(‘root’));
root.render(<App />);
“`
Also Read: How To Hire ReactJS Developer
Automatic batching
React 18 introduces a powerful feature that automatically combines multiple state updates, resulting in fewer re-renders for components. This batching mechanism enhances performance by consolidating several updates into a single re-render, which helps to avoid unnecessary rendering cycles.
Prior to this update, React only batched state updates that occurred within its event handlers, leaving updates from promises, `setTimeout`, native event handlers, and similar situations ungrouped. With the advent of automatic batching, these updates are now efficiently batched, further streamlining the rendering process and enhancing overall application performance.
Concurrent rendering
If there were a single word to encapsulate the entire React 18 update, it would be “Concurrency.” This feature enables React to divide extensive updates into smaller segments, allowing the browser to handle updates more effectively.
In essence, concurrency allows tasks to overlap, meaning that one state update does not need to be entirely finished before transitioning to the next. It permits the system to shift between multiple tasks, pausing one task if needed to prioritise more urgent ones.
This does not imply that all tasks are executed simultaneously, but rather that a task can now be temporarily halted while others are addressed.
Suspense Features
True to its name, Suspense pauses rendering until the required resources are available. This feature allows developers to declaratively define the loading state for specific sections of the component tree when they are not yet prepared for display. By using Suspense, you can seamlessly manage loading indicators and enhance user experience while waiting for data or components to load.
Referring to the code above, the `ReadyComponent` will no longer be mounted immediately; instead, it will wait for the `ComponentWaitingForData` to fully resolve before proceeding.
New Hooks
useId
The `useId` hook is a new addition designed to create unique IDs for use on both the client and server, effectively preventing hydration mismatches. This capability is particularly beneficial for component libraries that interact with accessibility APIs needing distinct identifiers. While this addresses a problem present in React 17 and earlier versions, its importance is amplified in React 18 due to the streaming server renderer’s ability to deliver HTML in a non-sequential manner.
useTransition
The `useTransition` hook, along with `startTransition`, allows developers to classify certain state updates as non-urgent. By default, other state updates are treated as urgent. This means that urgent updates, like those triggered by user input in a text field, can interrupt and take precedence over non-urgent updates, such as rendering a list of search results. This functionality ensures a smoother user experience by prioritizing immediate interactions while managing less critical updates in the background.
useDeferredValue
The `useSyncExternalStore` hook is a recent addition that enables external data stores to support concurrent reads by making updates to the store synchronous. This eliminates the necessity of using `useEffect` for setting up subscriptions to external data sources. It is highly recommended for any library that interacts with state that exists outside of React.
useInsertionEffect
The `useInsertionEffect` hook is a new feature aimed at helping CSS-in-JS libraries tackle performance challenges related to style injection during rendering. While it’s not expected that most developers will utilize it unless they’ve created a CSS-in-JS library of their own, this hook operates after the DOM has been updated but before any layout effects can read the new layout.
This enhancement addresses a limitation seen in React 17 and earlier versions, but it gains significance in React 18 due to React’s ability to yield control to the browser during concurrent rendering, thereby allowing it to recalculate layouts effectively.
Read More: 15 Best Leading React Carousel Libraries
Conclusion:
In conclusion, React 18 brings with it an array of new features and improvements designed to enhance developer productivity and improve user experience. From the introduction of Suspense for data fetching to the useSyncExternalStore hook, these additions are aimed at simplifying complex tasks and improving performance. As a developer, keeping up with these changes will be crucial in ensuring that your apps remain up-to-date and optimized for optimal performance. With React constantly evolving, it’s important to stay informed about its latest updates and enhancements.
