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React has always been the library of choice for developing dynamic and high-performance web applications, and every new version has pushed the limits of what we can do. In React 19, we have started a new chapter of innovation that will continue to prioritize performance, developer experience, and pushing the boundaries of what is possible with React.
In this blog post, we'll explore the key enhancements in React 19, and I’m excited to share how this release will change how you think about building applications. Whether you’re a seasoned React developer or just starting your journey, this blog post will cover some of the most exciting improvements and features in React 19 and the reasons why you should be excited about it!
What's New in React 19?
React 19 comes with some of the significant changes that are made to reduce the complexity and increase the performance:
Actions: Simplify data mutations and state updates with async functions.
New Hooks: Optimize state management and form handling with useOptimistic, useActionState, and useFormStatus.
Improved Hydration: Faster and more efficient server-side rendering.
Enhanced Context API: Performance improvements and some easier patterns to consume context.
Support for Custom Elements: You can now seamlessly use web components built with the platform-agnostic custom elements library.
Let's look at them one by one with examples.
Actions: Streamlining Asynchronous Operations
Handling asynchronous work like form submissions or API requests often requires dealing with a loading state, error state, and optimistic updates. React 19 introduces Actions, allowing you to use async functions within transitions to help manage these cases more easily.
Example: Simplifying Form Submission
Traditionally handling form submissions was a thing like managing many state variables:
function UpdateName() {
const [name, setName] = useState('')
const [error, setError] = useState(null)
const [isPending, setIsPending] = useState(false)
const handleSubmit = async () => {
setIsPending(true)
try {
await updateName(name)
} catch (err) {
setError(err)
} finally {
setIsPending(false)
}
}
return (
<div>
<input value={name} onChange={(e) => setName(e.target.value)} />
<button onClick={handleSubmit} disabled={isPending}>
Update
</button>
{error && <p>{error.message}</p>}
</div>
)
};
With Actions in React 19, this process becomes more straightforward:
function UpdateName() {
const [name, setName] = useState('')
const [error, submitAction, isPending] = useActionState(
async (prevState, formData) => {
await updateName(formData.name)
}
)
return (
<form action={submitAction}>
<input
name="name"
value={name}
onChange={(e) => setName(e.target.value)}
/>
<button type="submit" disabled={isPending}>
Update
</button>
{error && <p>{error.message}</p>}
</form>
)
}
This approach reduces boilerplate code and enhances readability, making it easier to manage asynchronous operations.
New Hooks: Enhancing State Management
React 19 comes with new hooks that make managing the state even easier.
useOptimistic: This hook makes it easier to do optimistic UI updates where you can update the interface before the server has confirmed a change.
useActionState: Manages Actions state, where you can know about pending operations or errors.
useFormStatus: Manages form submission state. Easily keep track of forms status.
Example: A UI component is great for dealing with optimistic update scenarios.
function LikeButton({ postId }) {
const [isLiked, setIsLiked] = useState(false)
const [optimisticIsLiked, setOptimisticIsLiked] = useOptimistic(isLiked, (prev) => !prev)
const handleLike = async () => {
setOptimisticIsLiked()
try {
await likePost(postId)
setIsLiked((prev) => !prev)
} catch (error) {
// handle error here
}
}
return (
<button onClick={handleLike}>
{optimisticIsLiked ? 'Unlike' : 'Like'}
</button>
)
}
This implementation ensures immediate feedback to the user, enhancing the overall experience.
Improved Hydration: Boosting Server-Side Rendering
React 19 brings a big improvement to the hydration process which makes it faster and more efficient server-side rendering, making it so interactive elements take less time to become functional resulting in a better user experience.
Example: Server-Side Rendering with Improved Hydration
Developers can take advantage of the improved hydration in React 19 to make server-rendered content more quickly interactive, which is especially valuable for users on slow networks.
Enhanced Context API: Optimizing Performance
The updated Context API in React 19 brings some performance optimization and introduces more intuitive patterns to consume context, which all lead to the effort for more efficient state management between components.
Example: Consuming Context with Enhanced API
The new Context API helps developers handle global state management more effectively which in turn leads to the reduced number of re-renders and better performing applications!
Support for Custom Elements: Integrating Web Components
React 19 brings in support for custom elements that let you use web components seamlessly in your React application. This means you can now easily use reusable components across multiple projects or frameworks.
Example: Using a Custom Element in React
Integrating a custom web component into a React application is now straightforward:
function App() {
return (
<div>
<my-custom-element prop="value"></my-custom-element>
</div>
)
}
This compatibility opens the doors for component reuse and interoperability between different technologies.
How to Upgrade to React 19
Prepare Your App:
Update to React 18.3 first to address any deprecations.
Use tools like React DevTools to profile your app for potential issues.
Install React 19:
bun add react@19 react-dom@19 # or npm install react@19 react-dom@19 # or yarn add react@19 react-dom@19
Test Thoroughly:
Ensure all dependencies are compatible with React 19.
Run your test suite and profile performance improvements.
Conclusion
React 19 is not an update, it's a completely new way to conceive modern web applications. Smarter compilers and better rendering techniques allow developers to build faster, more interactive, and scalable apps than ever seems good enough while building your next complex SaaS product, dynamic e-commerce, or the new social media in the market.
Dive into React 19, play with its new features, and let’s create something amazing. Happy coding!