auth0-react

What this skill does

# Auth0 React Integration

Add authentication to React single-page applications using @auth0/auth0-react.

---

## Prerequisites

- React 16.11+ application (Vite or Create React App) - supports React 16, 17, 18, and 19
- Auth0 account and application configured
- If you don't have Auth0 set up yet, use the `auth0-quickstart` skill first

## When NOT to Use

- **Next.js applications** - Use `auth0-nextjs` skill for both App Router and Pages Router
- **React Native mobile apps** - Use `auth0-react-native` skill for iOS/Android
- **Server-side rendered React** - Use framework-specific SDK (Next.js, Remix, etc.)
- **Embedded login** - This SDK uses Auth0 Universal Login (redirect-based)
- **Backend API authentication** - Use express-openid-connect or JWT validation instead

---

## Quick Start Workflow

### 1. Install SDK

```bash
npm install @auth0/auth0-react
```

### 2. Configure Environment

**For automated setup with Auth0 CLI**, see [Setup Guide](references/setup.md) for complete scripts.

**For manual setup:**

Create `.env` file:

**Vite:**
```bash
VITE_AUTH0_DOMAIN=your-tenant.auth0.com
VITE_AUTH0_CLIENT_ID=your-client-id
```

**Create React App:**
```bash
REACT_APP_AUTH0_DOMAIN=your-tenant.auth0.com
REACT_APP_AUTH0_CLIENT_ID=your-client-id
```

### 3. Wrap App with Auth0Provider

Update `src/main.tsx` (Vite) or `src/index.tsx` (CRA):

```tsx
import React from 'react';
import ReactDOM from 'react-dom/client';
import { Auth0Provider } from '@auth0/auth0-react';
import App from './App';

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <Auth0Provider
      domain={import.meta.env.VITE_AUTH0_DOMAIN} // or process.env.REACT_APP_AUTH0_DOMAIN
      clientId={import.meta.env.VITE_AUTH0_CLIENT_ID}
      authorizationParams={{
        redirect_uri: window.location.origin
      }}
    >
      <App />
    </Auth0Provider>
  </React.StrictMode>
);
```

### 4. Add Authentication UI

```tsx
import { useAuth0 } from '@auth0/auth0-react';

export function LoginButton() {
  const { loginWithRedirect, logout, isAuthenticated, user, isLoading } = useAuth0();

  if (isLoading) return <div>Loading...</div>;

  if (isAuthenticated) {
    return (
      <div>
        <span>Welcome, {user?.name}</span>
        <button onClick={() => logout({ logoutParams: { returnTo: window.location.origin } })}>
          Logout
        </button>
      </div>
    );
  }

  return <button onClick={() => loginWithRedirect()}>Login</button>;
}
```

### 5. Test Authentication

Start your dev server and test the login flow:

```bash
npm run dev  # Vite
# or
npm start    # CRA
```

---

## Detailed Documentation

- **[Setup Guide](references/setup.md)** - Automated setup scripts (Bash/PowerShell), CLI commands, manual configuration
- **[Integration Guide](references/integration.md)** - Protected routes, API calls, error handling, advanced patterns
- **[API Reference](references/api.md)** - Complete SDK API, configuration options, hooks reference, testing strategies

---

## Common Mistakes

| Mistake | Fix |
|---------|-----|
| Forgot to add redirect URI in Auth0 Dashboard | Add your application URL (e.g., `http://localhost:3000`, `https://app.example.com`) to Allowed Callback URLs in Auth0 Dashboard |
| Using wrong env var prefix | Vite uses `VITE_` prefix, Create React App uses `REACT_APP_` |
| Not handling loading state | Always check `isLoading` before rendering auth-dependent UI |
| Storing tokens in localStorage | Never manually store tokens - SDK handles secure storage automatically |
| Missing Auth0Provider wrapper | Entire app must be wrapped in `<Auth0Provider>` |
| Provider not at root level | Auth0Provider must wrap all components that use auth hooks |
| Wrong import path for env vars | Vite uses `import.meta.env.VITE_*`, CRA uses `process.env.REACT_APP_*` |
| Using `acr_values` redirect for in-app MFA | Use `useAuth0().mfa` API for in-app enrollment/challenge/verify flows |
| Not catching `MfaRequiredError` | Wrap `getAccessTokenSilently` in try/catch and check `instanceof MfaRequiredError` |
| Making direct HTTP calls to MFA endpoints | Use the `mfa` property from `useAuth0()` — it handles token management automatically |
| Forgetting refresh tokens for step-up MFA | Set `useRefreshTokens={true}` on Auth0Provider when using `interactiveErrorHandler="popup"` |

---

## Related Skills

- `auth0-quickstart` - Basic Auth0 setup
- `auth0-migration` - Migrate from another auth provider
- `auth0-mfa` - Add Multi-Factor Authentication
- `auth0-cli` - Manage Auth0 resources from the terminal

---

## Quick Reference

**Core Hooks:**
- `useAuth0()` - Main authentication hook
- `isAuthenticated` - Check if user is logged in
- `user` - User profile information
- `loginWithRedirect()` - Initiate login
- `logout()` - Log out user
- `getAccessTokenSilently()` - Get access token for API calls
- `mfa` - MFA API client for enrollment, challenge, and verification
  - `mfa.getAuthenticators(mfaToken)` - List enrolled authenticators
  - `mfa.getEnrollmentFactors(mfaToken)` - Get available enrollment factors
  - `mfa.enroll(params)` - Enroll new authenticator (OTP, SMS, Email, Voice, Push)
  - `mfa.challenge(params)` - Initiate MFA challenge
  - `mfa.verify(params)` - Verify MFA challenge and complete authentication

**MFA Error Types (import from `@auth0/auth0-react`):**
- `MfaRequiredError` - Thrown by `getAccessTokenSilently` when MFA is needed (has `mfa_token` and `mfa_requirements`)
- `MfaEnrollmentError`, `MfaChallengeError`, `MfaVerifyError` - Thrown by respective `mfa.*` methods

**Common Use Cases:**
- Login/Logout buttons → See Step 4 above
- Protected routes → [Integration Guide](references/integration.md#protected-routes)
- API calls with tokens → [Integration Guide](references/integration.md#calling-apis)
- Error handling → [Integration Guide](references/integration.md#error-handling)
- MFA handling → [Integration Guide](references/integration.md#mfa-handling)

---

## References

- [Auth0 React SDK Documentation](https://auth0.com/docs/libraries/auth0-react)
- [Auth0 React Quickstart](https://auth0.com/docs/quickstart/spa/react)
- [SDK GitHub Repository](https://github.com/auth0/auth0-react)