React 19 New Features: Complete Guide to the Latest Updates and Breaking Changes

React 19: A New Era

React 19 brings significant improvements to developer experience and performance. Let's explore the major new features.

Server Components

Server Components run on the server, reducing JavaScript bundle size:

// This component runs on the server
async function BlogPosts() {
  const posts = await db.posts.findMany();
  return (
    

      {posts.map(post => (
        
{post.title}
      ))}
    
  );
}

Actions

Actions simplify form handling and data mutations:

function ContactForm() {
  async function submitForm(formData: FormData) {
    'use server';
    await saveContact(formData);
  }

  return (
    

      
      Submit
    
  );
}

The use() Hook

A new hook for consuming promises and context:

function Comments({ commentsPromise }) {
  const comments = use(commentsPromise);
  return comments.map(c => 
{c.text}
);
}

Key Takeaways

1. Server Components reduce client-side JavaScript
2. Actions simplify form and mutation handling
3. The use() hook enables cleaner async patterns