🔐 React Error Boundaries – Catch JavaScript Errors in Components (2025 Guide)

---

🧲 Introduction – Why Use Error Boundaries?

In React.js, JavaScript errors in a component tree can break the entire UI, leading to blank screens and frustrated users. React Error Boundaries are the solution.

An Error Boundary is a special component that catches JavaScript errors anywhere in its child component tree, logs them, and displays a fallback UI without crashing the whole app.

🎯 In this guide, you’ll learn:

• What Error Boundaries are and how they work
• How to create and implement one
• Best practices and common use cases
• Limitations and how they compare to try/catch

---

📦 1. What Are Error Boundaries?

Error Boundaries are React class components that implement lifecycle methods to catch rendering errors and provide fallback UIs.

📌 They catch errors during:

• Rendering
• Lifecycle methods
• Constructors of child components

📌 They do NOT catch:

• Asynchronous code (setTimeout, fetch)
• Event handlers
• Server-side rendering errors

---

⚙️ 2. Create a Basic Error Boundary

import React from 'react';

class ErrorBoundary extends React.Component {
  constructor(props) {
    super(props);
    this.state = { hasError: false, error: null };
  }

  static getDerivedStateFromError(error) {
    return { hasError: true, error };
  }

  componentDidCatch(error, errorInfo) {
    console.error('Error caught:', error, errorInfo);
    // Optionally log to external services like Sentry
  }

  render() {
    if (this.state.hasError) {
      return <h2>Something went wrong 😢</h2>;
    }

    return this.props.children;
  }
}

export default ErrorBoundary;

---

✅ Usage:

<ErrorBoundary>
  <MyComponent />
</ErrorBoundary>

✅ Catches any error thrown inside <MyComponent>
✅ Displays fallback UI without breaking the app

---

🧠 3. Error Boundary with Custom Fallback UI

function FallbackUI({ error, reset }) {
  return (
    <div className="error">
      <h2>Oops! {error.message}</h2>
      <button onClick={reset}>Try Again</button>
    </div>
  );
}

✅ Modify Error Boundary:

render() {
  if (this.state.hasError) {
    return this.props.fallback || <FallbackUI error={this.state.error} />;
  }

  return this.props.children;
}

✅ Flexible fallback rendering
✅ Support for reset and recovery

---

💡 4. Best Places to Use Error Boundaries

Use Case	Reason
🖼️ Component galleries	Prevent 1 failed widget from crashing all others
📄 Content blocks	Show fallback for broken sections only
🔄 Route wrappers	Catch per-page crashes (404s, SSR errors)
🔒 Auth areas	Guard against runtime errors on login/logout flows

---

🧪 5. Error Boundaries vs try/catch

Feature	Error Boundary	try/catch block
Scope	Renders + lifecycle	Synchronous JS only
Works in UI render	✅ Yes	❌ No (throws error)
Asynchronous errors	❌ No	✅ Yes (with async/await)
Used for	Visual fallback	Control flow

📘 Use try/catch for async logic; use error boundaries for UI rendering errors

---

🚀 6. Tools That Use Error Boundaries

• React DevTools: Help detect and isolate boundary breaks
• Sentry, LogRocket, Datadog: Capture errors via componentDidCatch
• Next.js: Supports per-page error boundaries for SSR/SPA fallback
• React Router: Supports boundaries via <ErrorBoundary> in route config

---

📘 Best Practices

✅ Create a global error boundary at the App level
✅ Use multiple boundaries for isolated features (modals, widgets, routes)
✅ Always log errors in componentDidCatch()
✅ Provide meaningful fallback UIs to enhance UX
✅ Reset boundary state on retries or route changes

---

📌 Summary – Recap & Next Steps

React Error Boundaries are vital for resilient user interfaces. They prevent a single component crash from breaking the entire app and improve debugging, logging, and user experience.

🔍 Key Takeaways:

• Use class components to create Error Boundaries
• Wrap unstable or remote-rendered components with boundaries
• Catch render and lifecycle errors—not async/event errors
• Pair with fallback UI and error tracking tools
• Use multiple boundaries for scoped recovery

⚙️ Real-World Relevance:
Used in production apps like Facebook, Jira, and Slack to catch UI failures gracefully and keep the interface running.

---

❓ FAQ Section

❓ Can I use Error Boundaries in functional components?
✅ Not directly. Error Boundaries must be class components, but you can wrap them around functional components.

---

❓ Do Error Boundaries catch async errors in fetch()?
❌ No. Use try/catch inside async functions to handle those.

---

❓ Can I use multiple Error Boundaries?
✅ Yes. It’s recommended to use multiple smaller boundaries to isolate failure.

---

❓ Are Error Boundaries available in React 18?
✅ Yes. They’re stable since React 16 and work in all React versions ≥16.

---

❓ Should I log errors in componentDidCatch()?
✅ Absolutely. Log them to services like Sentry, Datadog, or your custom logger.

---

Share Now :