Top 9 Game-Changing Features in React 19 You Need to Know

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Here is a lot of excitement in the React world, and for good reason. It’s not just another small update; React 19 is here. This version is a big change because it focuses on making things easier for developers and giving them big performance boosts right away. A lot of once experimental features are now stable, giving every React developer access to powerful tools.

React 19 is here to help if you’ve ever felt stuck trying to optimise things by hand or wanted an easier way to do things like submitting forms and getting data. The framework does a lot of the hard work for you, so you can write cleaner, easier-to-understand code.

Let’s look at the top 9 features in React 19 that will change the way you make apps.

1. The React Compiler

The new React Compiler is probably the most magical part of React 19. For a long time, we’ve used useMemo, useCallback, and memo() to manually improve our components and stop them from re-rendering when they don’t need to. This method is powerful, but it can make your code messy and add extra work for your brain.

The React Compiler makes everything easier by taking care of these optimisations for you. It looks at your JSX and turns it into optimised vanilla JavaScript, so you don’t have to do any manual memoization. This means that you can write simpler components, and React will make sure they work well.

Benefit: Cleaner code, less boilerplate, and better performance by default without manual tweaking. 

javascript
// In React 19, you can just write this...
function MyComponent({ items }) {
  const [query, setQuery] = useState("");
  const filteredItems = items.filter(item => item.name.includes(query));

  return (
    <div>
      <input value={query} onChange={e => setQuery(e.target.value)} />
      <ItemList items={filteredItems} />
    </div>
  );
}

// ...and the compiler automatically optimizes it, as if you had used useMemo.
// No more const filteredItems = useMemo(() => ..., [items, query]);

2. Server Components & Directives

Server Components were first introduced in frameworks like Next.js, but they are now a key part of React. These parts only run on the server, which means they can directly access server-side resources, such as databases and file systems.
This makes the JavaScript bundle on the client side much smaller because the logic for the component never goes to the browser. The outcome is a quicker first page load and better SEO.
React 19 adds two directives to tell the difference between server and client environments:

  • 'use client': Placed at the top of a file, this marks the component (and its children) as Client Components, allowing them to use state and interactivity (useState, useEffect, etc.).
  • 'use server': This marks functions that can be called from the client but execute securely on the server. We’ll see this with Actions.

Benefit: Drastically improved performance, smaller bundle sizes, and the ability to seamlessly blend server-side data fetching with client-side interactivity.

3. Actions for Simplified Mutations

There has always been a lot of boilerplate code involved in handling form submissions and data changes. Actions make this easier by letting you send a function directly to a form‘s action prop.

Actions can happen at the same time or at different times. When used with the use server directive, they turn into Server Actions, which let client-side components easily call server-side functions without having to make separate API endpoints.

Benefit: Easier form handling and server-side changes, which means you don’t have to use useEffect and useState to keep track of submission states. 

// actions.js
'use server';

export async function updateUser(formData) {
 const name = formData.get('name');
 // ...logic to update user in the database
 console.log(`User name updated to: ${name}`);
}

// UpdateUserForm.jsx
'use client';
import { updateUser } from './actions';

function UpdateUserForm() {
 return (
   <form action={updateUser}>
     <input type="text" name="name" />
     <button type="submit">Update Name</button>
   </form>
 );
}

How do you think Server Actions will change the way you structure your full-stack applications?

4. New Hooks: useActionState, useFormStatus, and useOptimistic

To support Actions, React 19 introduces a trio of powerful hooks:

  • useActionState: This hook keeps track of the state of an action. You can see the pending state and the data that comes back from the action (like success or error messages), which makes it easy to give users feedback.
  • useFormStatus: This hook provides status information about a parent submission. It’s perfect for creating reusable design system components, like a submit button that automatically disables itself and shows a “Saving…” message when the form is pending.
  • useOptimistic: With the assumption that an async action would be successful, this hook enables you to perform a “optimistic” UI refresh right away. Your application seems responsive right away. React automatically returns the user interface to its initial state if the action is unsuccessful.

Benefit: Granular control over form and action states, leading to better UX with less complex state management logic. 

// Example using useFormStatus in a button component
import { useFormStatus } from 'react-dom';

function SubmitButton() {
 const { pending } = useFormStatus();

 return (
   <button type="submit" disabled={pending}>
     {pending ? 'Submitting...' : 'Submit'}
   </button>
 );
}

5. The Versatile use Hook

The new use hook makes it possible to read values from resources like Promises or Context right in your render logic, which is a big deal. You can call use inside conditionals or loops, which is not the case with other hooks.

When you pass a promise to use, it “unwraps” it. The component will stop rendering until the promise is fulfilled, at which point it will return its value. This works perfectly with Suspense to handle loading states and Error Boundaries to handle error states.

Benefit: Simplifies data fetching and context consumption, allowing for cleaner code by removing the need for useEffect for data loading or useContext for reading context. 

import { use } from 'react';
import { fetchProducts } from './api';
import { ThemeContext } from './ThemeContext';

function ProductPage() {
 // Read a value from context
 const theme = use(ThemeContext);

 // Read a value from a Promise
 const products = use(fetchProducts());

 return (
   <div className={theme}>
     {products.map(product => <div key={product.id}>{product.name}</div>)}
   </div>
 );
}

6. ref as a Prop

The forwardRef higher-order component has been a source of confusion and extra code for a long time. You don’t need to do this anymore in React 19! You can now send a ref directly to a functional component as a prop. It’s a small change that makes the code much clearer.

Benefit: Simpler and more intuitive ref forwarding, making component code cleaner and easier to understand. 

// Before React 19
const MyInput = React.forwardRef((props, ref) => {
 return <input {...props} ref={ref} />;
});

// With React 19
function MyInput({ ref, ...props }) {
 return <input {...props} ref={ref} />;
}
  1. Built-in Document Metadata Support

In the past, you needed third-party libraries like React Helmet to handle <title>, <meta>, and <link> tags for SEO. This feature is now part of the core library in React 19. You can now put these tags directly in your components, and React will automatically move them to the document <head>.

Benefit: Native SEO management, ensuring your document head is always in sync with your rendered components without extra dependencies. 

function ProductPage({ product }) {
 return (
   <div>
     <title>{product.name}</title>
     <meta name="description" content={product.description} />
     <h1>{product.name}</h1>
     <p>{product.description}</p>
   </div>
 );
}

8. Enhanced Resource Preloading

Performance is a big deal, and React 19 adds new APIs that let you control how resources are loaded in great detail. You can use functions like preload and preinit to tell React to load stylesheets, fonts, and scripts before they are needed. React does a smart job of handling this by stopping duplicate requests and making sure that resources are loaded at the right time.

Benefit: Faster perceived performance and smoother user experiences by proactively loading critical assets.

Which of these new features are you most excited to integrate into your projects? Share your thoughts in the comments below!

9. Better Error Reporting

Lastly, debugging in React 19 is getting a new look. React now gives clearer, shorter error messages instead of a lot of confusing logs for the same problem. In particular, hydration error messages are much more helpful because they show the difference between what was expected and what was shown.

Benefit: A less frustrating debugging experience, helping you find and fix issues faster.

What Will You Build First?

React 19 is a huge update that improves many of React’s core ideas and adds powerful new tools. These features, like the compiler’s automatic optimizations and the ease of use of Server Actions, let us make apps that are faster, more efficient, and easier to maintain.

It’s your turn now. You could try making a small part that uses one of these new features, like a form with a Server Action or a part that gets data when you use it. Please leave a link to your CodePen or a screenshot in the comments below. I’d love to see what you make!

Take the Next Step: Follow & Build

React 19 is here, and the best way to master it is by building. While you’re crafting your next project with the Compiler and Server Actions, stay connected with us for more deep dives, tutorials, and development insights.

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