React 19: What’s New, Latest Features, and Updates

Reactjs, a leading force in mobile app development, desktop applications, and cross-platform development, owes much of its success to its vibrant community. We're captivated by React's capabilities and users' passions. React has now introduced React 19 beta (we apologize for the delay in sharing this news). So, let's explore all the changes and new tools together.

Before we start, every blog is complete with some numbers. So here we go. According to research done by trends.builtwith over 45 Million live websites using React. Now, we have stats out of the way. Let’s dive deep into React 19.

Keep in mind that React 19 is still a work in progress. Follow the official site and social media guide to stay updated on the latest developments

The latest version of React 18.2.0 was launched on (April 25, 2024) with some changes, and here is the list of changes.

• Allow writing to this. refs to support string ref codemod 909071
• Warn for deprecated findDOMNode outside StrictMode c3b283
• Warn for deprecated test-utils methods d4ea75
• Warn for deprecated Legacy Context outside StrictMode 415ee0
• Warn for deprecated string refs outside StrictMode #25383
• Warn for deprecated default props for function components #25699
• Warn when spreading key #25697Warn when using act from test-utils d4ea75
  

If you have to go through the full list of changes, check it out here

React 19: Features and Overview

React 19 introduces several significant updates and features to improve developer experience and application performance.

1. Server Components
   
   These components perform their tasks on the server before sending the finished page to the user, Improving load times and SEO. They enable more efficient handling of data and interactions on the server side.
   
   
2. Improved Asset Loading
   
   React 19 preloads images and other assets in the background while users still view the current page, reducing wait time when navigating to new pages.
   
   
3. Document Metadata
   
   A new <DocumenHead> component simplifies adding titles, meta tags, and other metadata to pages, benefiting SEO and ensuring consistent site branding.
   
   
4. Web Components Integration
   
   React 19 improves compatibility with web components, allowing developers to integrate custom elements seamlessly into their React applications.
   
   
5. React Compiler
   
   The new React compiler automates re-renders, eliminating the need for manual optimizations using hooks like useMemo() and user callback ().
   
6. Improved Hooks
   
   New hooks, such as useOptimistics, allow for optimistic UI updates and enhance the user experience by making the interface more responsive.
   
   
7. Concurrent Rendering
   
   This feature enables faster time-to-interaction by allowing React to prepare and render components in the backgrounds, making the application feel snappier.
   
   
8. Action API
   
   This API helps manage data transmission from the client to the server, supporting sync and functions and improving interactivity during data fetching operations.
   

You can find the code for all the examples on my GitHub here. Alright, Let's start from the top! React 19 and its new features

1. Server Components

Run on the server instead of the client (your browser). When you visit a website, these components prepare the page on the server and then send it to your browser. React 19 also includes all the React Server Components features included from the Canary channel. This means libraries that ship with Server Components can now target React 19 as peer Dependency with a (react-server) for use in frameworks that support the Full-Stack React Architecture.

Benefits

• Faster Load Times: Pages load quicker since the server does most of the work.
  
  
• Better SEO: Search engines can easily read server-rendered pages, improving your site's ranking.
  
  
• Smooth Data Handling: Handling data on the server can make interactions on the website smoother and faster.
  

Example

// MyServerComponent.server.js
Export default function MyserverComponent()
{
Const data= fetchDataFromAPI();// Data feteched on server
return(
<div>
<h1>Data from Server</h1>
<p>{data}</p>
</div>
)
}

In this example, fetchDataFromAPI() runs on the server, fetching data and rendering it before sending the complete HTML to the client.

2. Improved Asset Loading

When the user navigated to a new page, assets like images and scripts loaded as needed. This could lead to delays and waiting times, as the browser had to fetch and load these assets on demand.

React 19 improves asset loading by preloading images, scripts, and other assets in the background while the user still views the current page. This proactive loading reduces the time users wait for assets to load when navigating to a new page.

Benefits:

• Reducing Waiting Time: Users experience less waiting when navigating between pages.
  
  
• Smoother Transition: Preloading assets makes transitions between page feel seamless.
  

Example

import React from 'react';
function MyComponent()
{
return
(
<div>
<img src="current-page.jpg" alt="current page"/>
<link rel="preload" href=""next-page.jpg" as="image"/>
</div>
);
}

export default MyComponent;

In this example, the <link rel="preload"> tag preloads <next-page.jpg> while user still views the current page.

3. Document Metadata

Managing document metadata(like titles and meta descriptions) often requires using third-party libraries or writing custom code to handle metadata changes dynamically.

React 19 introduces <DocumentHead>, a new component to easily add titles, meta tags, and other metadata to your pages. In the past, these elements would need to be inserted manually in effect or by libraries like react-helmet, requiring careful handling when the server renders a react component.

Benefits

• Improved SEO: Search engines use metadata to understand better and rank your site.
  
  
• Consistent Branding:- Ensure important information like titles and descriptions are consistent across all pages without repeating code.
  

Example

Using <DocumentHead> in a React Component:

function BlogPost({post})
{
return 
(
<article>
<h1>{post.title}</h1>
<meta name="author" content="name"/>
<link rek="author" href="https://x.com"/>
<meta name="keywords" content={post.keywords}/>
<p>
para
</p>
</article>
);
}

4. Web Components Integration

React 19 makes it easier to use Web Components within React applications. Our components are reusable pieces of code that work across different web frameworks.

React 19 enhances support for Web Components, making it easier to integrate custom elements within React applications. This update simplifies the process of using Web Components alongside React components.

Benefits

• Reusability:- You can use the same component across different projects and frameworks without significant modifications.
  
  
• Flexibility:- Easier integration of third-party components reduces the need for custom development and speeds up the development process.
  

Example

import React from 'react';

class MyCustomElement extends HTMLElement
{
connectedCallback()
{
this.innerHTML= '<p>This is a custom element</p>';
	}
}
customElement.define('my-custom-element',MyCustomElement);
export default function MyApp()
{
return
(
<div>
<h1>My React App</h1>
<my-custom-element></my-custom-element>
</div>
	);
}

5. React Compiler

Optimizing React applications for performance often required manual intervention, using hooks like <UseMemo>, <useCallback>, and <memo> to prevent unnecessary re-renders.

The new React Compiler in React 19 automates many of these optimizations, handling re-renders and performance tweaks automatically. This reduces the need for developers to manage these aspects manually.

While this will be released soon, you can learn more about this compiler from this resource.

• React Compiler Video
• React Compiler podcast episode

Benefits

1. Automatic Optimization:- React optimizes re-renders, reducing the need for manual hooks.
   
   
2. Simplified Code:- Developers can write simpler, cleaner code without worrying about performance tweaks.
   

Example

import React,{useMemo} from 'react';

function ExpensiveComponent({data})
{
const processdData = useMemo(()=> processData(data), [data]);
return <div>{processedData}</div>;

}

With React 19, the compiler automatically handles such optimizations, making the code cleaner and easier to maintain.

6. Improved Hooks

React hooks provided powerful tools for managing state and effects, but some scenarios still required complex workarounds or additional code to handle efficiently. With React 19, new hooks like ‘useoptimistic’ and ‘use’ offer better ways to manage state and handle asynchronous data fetching.

Benefits

• Optimistic Update:- ‘useoptimistic’ allows the UI to update immediately before the server confirms the change, improving user experience.
  
  
• Simpler Data Fetching:- The ‘use’ hook simplifies handling promises directly in your component, making asynchronous data fetching more straightforward.

Example

Using 'use optimistic' for optimistic UI update

import React from 'react';
import {useOptimistic} from 'react';

function updateName({currentname})
{
const [optimisticName, setOptimisticName]= useOptimistic(currentName);

const handlechange = async (newName)=> 
{
setOptimisticName(newName);
await savenameToServer(newName); // simulate server update
};

return
(
<div>
<p> Your names is: {optimisticName}</p>
<input type="text" onChange={(e)=> handleChange(e.target.vale)}/>
</div>

	);

}

This example demonstrates how useOptimistic can provide immediate feedback to the user while waiting for a server response.

7. Concurrent Rendering

Rendering in React was synchronous, meaning that complex components could block the main thread, making the application feel sluggish, especially during intensive tasks.

Concurrent rendering in React 19 allows components to be prepared and rendered in the background without blocking the main thread, making the app feel faster and more responsive.

Benefits

• Faster Interaction:- Users can interact with the app more quickly as rendering happens in the background.
  
  
• Improved Performance:- Better handling of heavy tasks without affecting the user experience.

Example

import React, {useTransition} from 'react';

function Mycomponent()
{
const[isPending, startTransition] = useTransition();

Cont handleClick = () => 
{
start Transition (() =>

{
// expensive task here
	};

};


return 
(
<button onClick={handleClick} disable={isPending}>
 {ispending > 'Loading....' : click Me'}
</button>

);
}

This example shows using <usetransition> to handle an expensive task in the background while keeping the UI responsive.

8. Action API

Handling form submissions and other user actions often required complex state management and asynchronous handling, which could lead to unresponsive UI during data processing. The Actions API in React 19 helps manage data submissions, supporting async functions and maintaining interactivity during data processing.

Benefit

• Smooth Interactivity:- This keeps the page interactive during data submission, providing a better user experience.
  
  
• Async Support:- Simplifies handling asynchronous actions with <async/await>, reducing the complexity of managing state and effects.

Example

Using the Action API for form submission

// server-component.js
import React from 'react';

export default function ServerComponent() {
  const data = fetchDataFromServer();
  return (
    <div>
      <h1>Data from Server</h1>
      <p>{data}</p>
    </div>
  );
}

async function fetchDataFromServer() {
  // Simulating a server-side data fetch
  return 'Server-side rendered content';
}

In this example, fetchDataFromServer simulates fetching data on the server-rendered within the component.

How Can I Use React 19 Now?

All these features are available in the Canary release, which you can learn more about here. As suggested by the team, do not use these for customer/user apps at the moment, but you can play around for fun!

If you’re interested in when React 19 is scheduled to be released, you can follow Canary Releases for updates.

Wrapping up React 19!

You have all the new features on React 19, from the new React Compiler to auto-rendering, memoization, state optimization, and UI. New hooks-like uses() will help you simplify promises and async code. Also, don’t forget about actions, web component integration, and enhanced performance.

Wait! There is more!

Third, Rock Techkno can help you with mobile and web app development if you are looking for a React developer. We have over a decade of experience in custom software development and offer a free consultation, so contact us here.

Frequently Asked Question(FAQs)

1. What is new in React 19?
   
   React 19 introduces a new React Compiler for optimized code, concurrent Rendering for faster interactions, Server Components for better SEO and load performance, and improved Hooks for more efficient state management.
   
   
2. How does concurrent rendering improve performance?
   
   Concurrent rendering allows React to work on multiple tasks simultaneously, making the UI more responsive and reducing time to interaction, especially for complex updates.
   
   
3. What are React Server Components?
   
   Server Components render parts of the UI on the Server, reducing the amount of JavaScript sent to the client. This results in faster load times and improved SEO.
   
   
4. How does the new React Compiler work?
   
   The React Compiler transforms react code into highly optimized Javascript, improving performance by reducing runtime costs and improving efficiency.
   
   
5. What Improvements have been made to React Hooks?
   
   New Hooks like useOptimistic and use provide better state management and handle asynchronous data fetching more efficiently, simplifying complex state logic.
   
   
6. What is the Action API in React 19?
   
   The Actions API helps manage data submission and asynchronous operations, maintaining interactivity during data processing with support for async/await and transitions.
   
   
7. How has asset loading been improved in React 19?
   
   React 19 preloads assets like images and scripts in the background, reducing wait time when users navigate to new pages and providing a smoother user experience.
   
   
8. What are the benefits of the new document metadata feature?
   
   The <DocumentHead> component allows for easier document metadata management directly within React components, improving SEO and ensuring consistent metadata across all pages.
   
   
9. How does React 19 handle global state management?
   
   React 19 introduces new tools for managing global states, simplifying state management across large applications, reducing boilerplate code, and making state logic more maintainable.