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swagath TP
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React 19: New Hooks Every Developer Should Know

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React 19 was officially released on npm on April 25, 2024. 
 
 This latest version brings a strong focus on enhancing performance and efficiency, along with exciting features designed to simplify web development and improve overall user experience.

What's new?

React 19 has some new features like automatic performance optimizations through the new React Compiler, server side rendering with Server Components for faster load times, enhanced concurrent rendering for smoother user experiences, etc.
One thing that caught my attention is the introduction of some brand-new hooks.

In this article, we'll look into these new hooks, explore their unique capabilities, and discuss how they can enhance your projects.

useTransition-Make slow tasks feel smooth

The useTransition() hook is designed for handling asynchronous operations by keeping your interface smooth and responsive.
It allows you to manage pending states and errors seamlessly, ensuring that your app doesn't freeze or become unresponsive during async tasks.

Have you ever clicked a button in an app and felt like it froze for a second? useTransition() can fix that.
It lets React handle loading in the background while keeping the app smooth and interactive. The UI can let users do other things, and when the data is ready, it updates without any delay.

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For example, you can use it to implement a "delete item" feature where the item disappears from the UI instantly, while the actual deletion happens in the background.

If the operation fails, useTransition allows you to handle errors gracefully without freezing the input or affecting the user experience, creating a more polished, responsive interface.
It's an essential tool for modern apps, especially when dealing with user interactions that depend on backend operations.

const Transition = () => {
 const [items, setItems] = useState(["Item 1", "Item 2", "Item 3"]);
 const [isPending, startTransition] = useTransition();
 const [error, setError] = useState(null);
const deleteItem = (itemToDelete) => {
 const updatedItems = items.filter(item => item !== itemToDelete);
 setItems(updatedItems);
 startTransition(() => {
 fakeDeleteAPI(itemToDelete)
 .then(() => {
 console.log(`${itemToDelete} deleted successfully.`);
 })
 .catch((err) => {
 setError(`Failed to delete ${itemToDelete}: ${err.message}`);
 setItems(items); 
 });
 });
 };
return (
 <div className="trans-container">
 <h1 className="trans-heading">Delete Item Example</h1>
 {error && <div className="error-message">{error}</div>}
 <ul className="item-list">
 {items.map((item) => (
 <li key={item} className="item">
 {item}
 <button className={`delete-button ${isPending ? "loading" : ""}`} onClick={() => deleteItem(item)}>
 {isPending ? "Processing…" : "Delete"}
 </button>
 </li>
 ))}
 </ul>
 {isPending && <p className="loading-indicator">Processing…</p>}
 </div>
 );
};
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useActionState-Manage action states easily

The useActionState() hook is a real-time saver when it comes to managing async actions.

If you've ever dealt with fetching data from an API or performing background tasks, you know how tricky it can be to track loading states, success, and errors.

This is where useActionState() steps in to simplify the process.
It automatically gives you access to the action's pending status, so you can easily show loading spinners or placeholder content while the operation is in progress.

Once the action is complete, it updates with the latest data, so you don't have to worry about manually managing the state or re-rendering components.

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For example, imagine you're building a user profile page that fetches user data from an API.
With useActionState, you can automatically display a loading while the data is being fetched, and once the data arrives, it's seamlessly updated on the page.

function UserDetails() {
 const [result, formAction, isPending] = useActionState(fetchUser, null);

 return (
 <div className="user-details-container">
 <h2 className="user-details-heading">Fetch User Information</h2>
 <form action={formAction} className="fetch-user-form">
 <button
 type="submit"
 className={`fetch-user-button ${isPending ? "loading" : ""}`}
 disabled={isPending}
 >
 {isPending ? "Loading…" : "Fetch User Info"}
 </button>
 </form>
{isPending ? (
 <div className="loading-indicator">Loading…</div>
 ) : result?.success ? (
 <div className="user-details">
 <p><strong>Name:</strong> {result.details.name}</p>
 <p><strong>Email:</strong> {result.details.email}</p>
 <p><strong>Age:</strong> {result.details.age}</p>
 </div>
 ) : result?.message ? (
 <p className="error-message">{result.message}</p>
 ) : null}
 </div>
 );
}
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useOptimistic-Make the updates feel instant

The useOptimistic() hook is a great tool for handling optimistic UI updates, making your app feel faster and more responsive.
If you've ever clicked a button and waited for a backend response before seeing the UI update.

This hook allows you to make temporary changes to the UI immediately while waiting for confirmation from the server.
If the backend operation succeeds, the temporary changes are finalized, but if it fails, useOptimistic automatically reverts the changes to maintain data consistency.

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In this Todo List app, the useOptimistic() hook lets users see new tasks instantly, even before the server confirms them.

If something goes wrong, like a network issue, the app removes the task and keeps everything in sync, ensuring a smooth and consistent experience for the user.

function Todo({ messages, sendMessage }) { 
 const formRef = useRef(); 

 async function formAction(formData) { 
 addOptimisticMessage(formData.get("message")); 
 formRef.current.reset(); 
 await sendMessage(formData); 
 } 

 const [optimisticMessages, addOptimisticMessage] = useOptimistic(
 messages, 
 (state, newMessage) => [
 …state, 
 { text: newMessage, sending: true }
 ]
 );
}
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By eliminating the delay between user actions and UI feedback, useOptimistic() creates a snappier and more engaging user experience.

Use-Simplify complex async workflows

The use() hook simplifies working with asynchronous resources, like promises and context, directly within the render phase.
Traditionally, managing async data in React required a combination of useEffect, useState, and conditional rendering for loading states.

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With use(), you can now fetch data or consume async resources seamlessly without juggling multiple hooks or adding unnecessary complexity to your components.

It's like cutting out the middleman and letting React handle async workflows natively.

function UsersList({ promise }) {
 const users = use(promise);
 return (
 <div>
 <h1>User List</h1>
 <ul>
 {users.map((user) => (
 <li key={user.id}>{user.name}</li>
 ))}
 </ul>
 </div>
 );
}
export default function App() {
 const [userPromise, setUserPromise] = useState(null);
 const handleLoadUsers = () => {
 setUserPromise(fetchUsers());
 };
}
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For instance, instead of using useEffect to fetch user data and update the state once the data arrives, you can now call the async function directly in your render code using use.

React will automatically pause rendering until the promise resolves, ensuring your UI updates only when the data is ready.
This not only simplifies your code but also makes it easier to reason about your components' behavior.

Conclusion

The new hooks like useTransition(), useActionState(), useFormStatus(), useOptimistic(), and use() will make development much more efficient.

They make coding simpler, save time by cutting out repetitive tasks, and improve the UI smoother.

Most importantly, they help create a better user experience, making apps faster, and more responsive. With these hooks, you'll find building modern, user-friendly applications quicker and more efficient than ever.

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