The new React 19 beta was released in April 2024 and stabilized in December of that year. This came only two years after the release of React 18. So, what’s new in React 19?
Surprisingly, React 19 introduces a host of new features, performance enhancements, and user experience improvements for developers. The biggest updates seem to focus on asynchronous state management, server-side rendering optimizations, and better error handling. All of this allows the simplification of complex workflows without sacrificing the flexibility React is known for.
In the rest of this article, we’ll look deeper at the most significant of React 19’s new features and cover everything you might need to know.
If you are interested in hiring an experienced React developer for your mobile and web applications, you are in the right place. Here at Trio, we have many nearshore and offshore developers with many years of experience using React. Our developers are at the forefront of the industry and can advise you on the best way forward.
Overview: New Features in React 19?
There are many new features and improvements that your React applications could take advantage of. The most notable ones that we have picked up and will be covering in this React 19 upgrade guide include features like:
- New React Hooks & APIs: React 19 introduces useActionState, useFormStatus, useOptimistic, and the use() API, which simplifies state and form management.
- React Actions: A new approach to handling form submissions and asynchronous transitions.
- React Server Components: A major update that improves server-side rendering and optimizes data fetching.
- DOM Enhancements & Static APIs: Enhancements such as <form> actions, improved script handling, and hydration error diffing.
- Performance Optimizations: Improved asset loading, stylesheet support, and better debugging tools.
New React Hooks & APIs
useActionState – Simplified Async State Management
Asynchronous state changes have always been challenging for developers. A new hook called useActionState is changing this, particularly when it comes to asynchronous state changes like UI updates and changes related to form submissions.
Here’s an example of what it might look like to use the new hook:
import { useActionState } from 'react';
function FormComponent() {
const [state, action] = useActionState(async (prevState, formData) => {
const response = await fetch('/submit', {
method: 'POST',
body: JSON.stringify(formData),
});
return response.json();
}, null);
return (
<form action={action}>
<input name=”email” type=”email” required />
<button type=”submit”>Submit</button>
</form>
);
}
useFormStatus – Improved Form State Handling
Real-time feedback is incredibly important for the overall user experience. The real-time feedback provided by the new useFormStatus hook – which, as the name suggests, relates to form submission states – can help your developers make important changes like enabling or disabling buttons or showing loaders dynamically whenever users interact with their forms.
import { useFormStatus } from ‘react’;
function SubmitButton() {
const { pending } = useFormStatus();
return <button type=”submit” disabled={pending}>{pending ? ‘Submitting…’: ‘Submit’}</button>;
}
useOptimistic – Optimistic UI Simplified
Optimistic updates, enabled by the useOptimistic hook – the last of the three new hooks – let you update your user interface before an asynchronous operation is completed. This gives your users an incredibly smooth experience and reduces the delays they perceive, even while your app waits for a server response. Let’s look at some code examples:
import { useOptimistic } from ‘react’;
function LikeButton() {
const [optimisticLikes, setOptimisticLikes] = useOptimistic(0);
async function handleLike() {
setOptimisticLikes(optimisticLikes + 1);
await fetch(‘/like’, { method: ‘POST’ });
}
return <button onClick={handleLike}>Likes: {optimisticLikes}</button>;
}
use() API – A Powerful New Async Solution
Along with the addition of new hooks, React 19 has also introduced new APIs.
Another tool for async operations, the use() API, gives your developers a new way to handle asynchronous operations within components. This means that you can handle async data more declaratively, making components simpler and easier to manage. The result is that you don’t need complex state management nearly as much when retrieving data.
Here’s what that might look like:
import { use } from ‘react’;
const dataPromise = fetch(‘/api/data’).then(res => res.json());
function DataComponent() {
const data = use(dataPromise);
return <div>{data.message}</div>;
}
React Actions – The Future of Form Handling
What are React Actions?
React Actions are a new way to handle form submissions and asynchronous transitions.
In the past, developers had to manage complex event handlers and state updates to deal with form data. With Actions, React provides a built-in mechanism to handle async transitions seamlessly.
Instead of relying on event listeners and manual fetch calls, React Actions integrate directly with the component lifecycle, making form submissions more declarative and reducing unnecessary state management. The result is that this built-in mechanism ends up handling async transitions seamlessly.
How Actions Improve Asynchronous Transitions
We’ve already mentioned that Actions simplify asynchronous workflows by enabling direct form submission handling within a React component. By automatically handling loading states, developers can focus on business logic rather than large amounts of boilerplate code.
Our developers have commented that this is a particularly big issue when working with state management tools like Redux, which often feel over-engineered but are still used because of the API they provide.
Here’s what a React Action might look like:
‘use server’;
async function submitForm(data) {
// Simulate the async operation
await new Promise(resolve => setTimeout(resolve, 1000));
return { success: true, message: “Form submitted successfully!” };
}
When a form is submitted, this is what you can expect on the client side:
import { useActionState } from ‘react’;
function ContactForm() {
const [state, action] = useActionState(submitForm, { success: false });
return (
<form action={action}>
<input name=”name” type=”text” required />
<input name=”email” type=”email” required />
<button type=”submit”>Send</button>
{state.success && <p>{state.message}</p>}
</form>
);
}
Real-World Examples of Actions in React 19
So, where can you use the Actions provided by this specific React version? The opportunities are endless, but some specific instances we’ve noticed are very popular.
Satte updates can be minimized in user authentication, like the kind you’d expect to see on a login and signup page. Data submissions are also a good place to use this feature. It allows you to send feedback forms or update user settings with automatic error handling.
Instant UI changes – while waiting for a server response – also allow for optimistic updates, as mentioned above.
React Server Components
What Are Server Components?
React Server Components (RSCs) are a new type of component that runs entirely on the server, which means they allow developers to offload rendering to the server.
This increases performance and stability by reducing client-side JavaScript bundle sizes and payloads, making it easier to build faster and more efficient applications.
To better understand the difference, let’s compare what a developer would have to do in the past with what they can now do using RSCs.
Here’s the old code:
// This component runs on the client, meaning the entire bundle must be downloaded
export default function UserProfile({ userId }) {
const [user, setUser] = useState(null);
useEffect(() => {
fetch(`/api/user/${userId}`)
.then(res => res.json())
.then(data => setUser(data));
}, [userId]);
if (!user) return <p>Loading…</p>;
return <h1>{user.name}</h1>;
}
This not only requires extra JavaScript but also increases client bundle size and execution time. Here’s what it would look like using RSCs:
‘use server’;
async function fetchUser(userId) {
const response = await fetch(`https://api.example.com/user/${
As you can see, the code itself is more efficient and will provide a better user experience.
One of the key aspects of React Server Components is that they allow developers to control rendering behavior through directives. A directive is a special instruction. In the code example above, it is ‘use server’, which tells React where a component should be executed. This further optimizes performance.
Server Actions
Server Actions are a key improvement in React 19 that helps eliminate unnecessary API calls. Instead of handling data mutations on the client side, developers can now execute server-side updates directly within components.
Here’s what they might look like:
‘use server’;
async function fetchUserData(userId) {
return await db.query(`SELECT * FROM users WHERE id = ${userId}`);
}
Similarly to the RSCs, which we’ve just discussed, they allow you to fetch and process data server-side, making the front end of your application less complex and, in turn, more efficient.
How to Use Server Components in React v19
To use RSCs after the React 19 release, your developers will need to start by defining their server-rendered components separately from their client components. They can then use server and client components together to balance rendering dynamically.
Here’s what it might look like to use server and client components together:
‘use client’;
import UserProfile from ‘./UserProfile.server’;
export default function Page() {
return (
<div>
<h1>My App</h1>
<UserProfile />
</div>
);
}
React DOM Enhancements & Static APIs
Although React DOM and static APIs are definitely not new, there have been some enhancements that make it easier to manage forms, scripts, hydration errors, and even third-party integrations.
One of the most significant updates in this category has been the new native support, which is available for <form> actions in the React DOM.
In the past, developers had to handle form submissions manually using onSubmit event handlers. The result would have been more state management and API calls from the client.
Here’s what it would look like:
<form action="/API/submit" method="post">
<input type="text" name="name" required />
<button type="submit">Submit</button>
</form>The new support means forms can submit data directly to server-side actions. This new feature also integrates seamlessly with RSCs to make form handling more declarative and efficient.
Another important improvement is the enhanced support for third-party scripts and browser extensions.
A lot of React applications rely on third-party services. Some common examples we’ve seen here at Trio include analytics tools, payment gateways, and embedded widgets.
In earlier versions, managing the execution and loading order of these scripts could be difficult, leading to performance issues or conflicts.
Now, you’ll have better control over when and how scripts load, allowing your developers to optimize their applications by delaying non-essential scripts until after the initial page render.
Hydration error handling is another aspect that has been improved. In previous versions, debugging hydration mismatches between server-rendered and client-rendered content was challenging due to vague error messages.
React 19 introduces detailed hydration error diffing, which pinpoints exactly where discrepancies occur between server-side and client-side rendering. This makes it much easier for developers to diagnose and fix issues related to dynamic content.
The way stylesheets and asset loading are managed has also been altered in the new version. In previous versions, dynamically changing stylesheets could lead to unnecessary re-renders or visual flickering.
Now, updates occur more efficiently without affecting performance. Styles, scripts, and images can also load in parallel, reducing initial page load times and enhancing the user experience.
Preloading and async script handling has also been refined. Developers can now specify critical resources that should be loaded, ensuring that essential styles and scripts are available as soon as they are needed and preventing delays caused by late-loading assets.
Finally, there’s better integration with custom elements and Web Components.
We’ve helped many companies use web components to encapsulate reusable UI logic. React’s improved handling of these elements ensures seamless communication between React-based components and non-React parts of an application, improving functionality and ease of integration.
Key Improvements in React 19
Enhancements to Component Composition
One of our favorite improvements in React 19 is the ability to pass ref as a prop directly to components. In previous versions, you would need to use workarounds such as using forwardRef, which made the code more complex. With React 19, you use a standard prop, simplifying component design and improving reusability.
This change reduces the friction involved in managing references and allows developers to write cleaner, more intuitive code, which is critical for sustainable software development and long-term success.
Our developers make a point of doing everything possible to keep their React code simple, sometimes even trying to write less code where possible so that future changes and maintenance are easy.
Another significant advancement in React 19 is the React Compiler, which optimizes performance by automatically transforming components to reduce unnecessary re-renders. The React Compiler enhances code efficiency by ensuring that components only update when truly necessary, improving both speed and responsiveness in large applications.
We know that React’s Context API has always been a powerful way to share state across a component tree, but the syntax often felt unnecessarily complicated and required a lot of boilerplate code. In React 19, <Context> itself can now serve as a provider without the need for a separate Provider component.
This small but impactful change streamlines the way in which global state is managed, which can be a big concern for many existing React apps, making the use of context more straightforward.
Memory management has also been improved, and cleanup functions for refs have been enhanced.
Manually cleaning up references was sometimes necessary to prevent memory leaks in the past, especially in components that were frequently mounted and unmounted. React 19 introduces a more efficient way to handle cleanup automatically, ensuring that unused references do not linger longer than necessary.
This enhancement leads to better performance, particularly in applications with complex UI interactions.
Additionally, useDeferredValue now supports an initial value, making it more flexible in handling transitions and deferred state updates. This change lets developers set a starting point for deferred values, making UI transitions feel more responsive without introducing unnecessary complexity.
Improved Asset Loading & Performance Optimization
We have already mentioned that React 19 improves how assets such as stylesheets, scripts, and images are loaded. Stylesheets now have better support for efficient loading, ensuring that styles are applied at the right time without causing layout shifts or unnecessary re-renders so you can dynamically switch themes or update styles on the fly.
Async script handling has also been enhanced so that you can load and execute third-party scripts more predictably instead of asynchronous loading requiring manual intervention to ensure scripts are executed in the correct order.
We think this will be pretty useful for analytics, advertising, and payment processing libraries, which often depend on scripts executing in a precise sequence.
Preloading and loading prioritization for assets has been improved, too. You can now mark critical resources for early loading, ensuring that important scripts and styles are available immediately, while less critical assets can be loaded later. Like many other improvements, this technique decreases initial page rendering times.
Compatibility with third-party scripts and browser extensions has also been refined. As discussed above, React applications frequently integrate with various external tools, and ensuring smooth compatibility is crucial.
Better Error Reporting & Debugging Tools
One of the most impactful changes that we’ve already mentioned is the more detailed hydration error messages, which lead to improved error handling in React 19.
As discussed, hydration errors could be cryptic, making it challenging to diagnose discrepancies between the server-rendered and client-rendered output. Error messages now pinpoint precisely where mismatches occur, allowing for a more straightforward fix.
Console warnings and logs have also been refined to provide more precise insights, grouping related warnings, preventing excessive logging in the console, and making it easier to identify the root cause of problems.
This is particularly beneficial when debugging applications with complex component hierarchies, where tracking down specific errors can otherwise be time-consuming.
These improvements in component composition, asset management, and debugging tools make React 19 a more developer-friendly framework.
How to Upgrade to React 19 – Step-by-Step Guide
1. Checking for Compatibility Issues
Before upgrading, confirming that your project and dependencies are compatible with React 19 is important. Many third-party libraries rely on React’s internal APIs; some may need updates to function correctly with the latest version. The first step is to check which dependencies are outdated by running:
npm outdated
This command lists all outdated dependencies, making it easier to identify which ones must be updated before upgrading to React 19. You should also review documentation from third-party libraries, such as Redux, React Query, and UI component libraries like Material UI or Chakra UI, to ensure they support React 19.
Checking the installed version of Node.js is recommended since React 19 may introduce improvements that depend on a newer Node.js release. Running the command below will display your current Node.js version:
node -v
If your version is outdated, upgrading to the latest Long-Term Support (LTS) version is best before proceeding with React 19.
2. Updating Dependencies
Once compatibility has been confirmed, the next step is to install React 19.
This can be done using either npm or Yarn. Running the following command will update both React and React DOM to the latest stable version:
npm install react@latest react-dom@latest
Or, if you are using Yarn:
yarn add react@latest react-dom@latest
After installing the update, it is important to verify that the correct versions are installed by running the following command
npm list react react-dom
This command should return a result showing that both React and React DOM are updated to version 19.0.0.
3. Migrating to New Features & APIs
Once the upgrade is complete, developers should start refactoring their code to take advantage of React 19’s improvements.
If your apps use server-side rendering, you can now incorporate React Server Components and Actions to reduce unnecessary JavaScript execution on the client. You can also convert Static components that do not require interactivity into Server Components by removing unnecessary client-side JavaScript.
It is also essential to check for deprecated lifecycle methods or patterns that may no longer be supported in React 19. Methods such as componentWillMount and componentWillReceiveProps are some examples of this.
Forms that rely on event listeners for submission handling can also be refactored to use the new form actions feature.
Conclusion
Although it has not been long since the release of version 18, React version 19 has proved to be a significant improvement of an already loved framework.
With new hooks like useActionState, useFormStatus, and useOptimistic, this version of React greatly simplifies state management. Other improvements will affect data handling and debugging, making React relevant even in 2025.
Upgrading your React apps is going to be essential. If you don’t take advantage of the new performance improvements, you risk falling behind your competitors. We’re here to help make the transition easy so your React projects are given the best chance to excell.
Our developers here at Trio are in the top 1%. We do not settle for anything less. If you want to get started updating your existing apps or putting together a React team, contact us for a free consultation.
Our solutions are not one-size-fits-all. Instead, we match you with the perfect people through staff augmentation or outsourcing so that you get what you need.
