How do Garfish's error handling and fallback mechanisms work, and how to ensure application stability?

Garfish's error handling and fallback mechanisms ensure that micro-frontend applications can gracefully degrade when exceptions occur, providing a good user experience.

Error Handling Mechanisms

1. Sub-application Loading Errors

• Error Types: Network errors, resource loading failures, script execution errors
• Handling Strategies:
  • Automatic retry mechanism
  • Provide error messages
  • Load fallback version
• Configuration Example:

javascript
{
  name: 'app1',
  entry: '//localhost:3001',
  errorBoundary: {
    onError: (error) => {
      console.error('Sub-application loading failed:', error);
      // Report error logs
      reportError(error);
    },
    fallback: () => {
      // Display fallback page
      return <ErrorPage message="Application loading failed, please try again later" />;
    }
  }
}

2. Runtime Errors

• Error Types: JavaScript runtime errors, component rendering errors
• Handling Strategies:
  • Use error boundaries to catch
  • Isolate error impact scope
  • Provide error recovery mechanism
• Example:

javascript
// React error boundary
class ErrorBoundary extends React.Component {
  componentDidCatch(error, errorInfo) {
    // Catch sub-application errors
    Garfish.emit('app-error', { error, errorInfo });
  }
  
  render() {
    if (this.state.hasError) {
      return <ErrorFallback />;
    }
    return this.props.children;
  }
}

3. Lifecycle Errors

• Error Types: bootstrap, mount, unmount execution failures
• Handling Strategies:
  • Catch lifecycle function errors
  • Ensure proper resource cleanup
  • Provide error callbacks
• Example:

javascript
export async function mount(container) {
  try {
    ReactDOM.render(<App />, container);
  } catch (error) {
    // Clean up rendered content
    container.innerHTML = '';
    throw error;
  }
}

Fallback Strategies

1. Application-Level Fallback

• Strategy: Display fallback page when sub-application loading fails
• Implementation:
  • Configure fallback component
  • Display static content
  • Provide retry button
• Example:

javascript
{
  name: 'app1',
  entry: '//localhost:3001',
  fallback: {
    component: () => (
      <div className="fallback">
        <h3>Application temporarily unavailable</h3>
        <button onClick={() => window.location.reload()}>
          Reload
        </button>
      </div>
    )
  }
}

2. Feature-Level Fallback

• Strategy: Degrade to simplified version when some features fail
• Implementation:
  • Detect feature availability
  • Provide alternative solutions
  • Gradually restore features
• Example:

javascript
// Check API availability
async function checkApiAvailability() {
  try {
    await fetch('/api/health');
    return true;
  } catch {
    return false;
  }
}

// Select implementation based on availability
const Component = apiAvailable ? FullFeature : SimplifiedFeature;

3. Performance Fallback

• Strategy: Reduce feature complexity when performance is insufficient
• Implementation:
  • Disable animation effects
  • Reduce data loading
  • Use simplified components
• Example:

javascript
// Detect device performance
const isLowPerformance = /low-performance/.test(navigator.userAgent);

// Select component based on performance
const AnimationComponent = isLowPerformance ? SimpleAnimation : FullAnimation;

Error Monitoring and Logging

1. Error Collection

• Collect error information from all sub-applications
• Record error context
• Standardize error format

2. Error Reporting

• Real-time error reporting to monitoring system
• Batch reporting to reduce network requests
• Support offline caching

3. Error Analysis

• Statistics on error frequency and types
• Analyze error impact scope
• Generate error reports

Best Practices

1. Error Prevention

• Comprehensive unit testing and integration testing
• Code review and quality checks
• Pre-release environment verification

2. Error Recovery

• Provide automatic retry mechanism
• Implement manual recovery options
• Save user state to avoid data loss

3. User Experience

• Friendly error messages
• Clear error explanations
• Provide solution suggestions

4. Monitoring and Alerts

• Set error threshold alerts
• Real-time error rate monitoring
• Quick response to critical errors

Through comprehensive error handling and fallback mechanisms, you can ensure the stability and reliability of micro-frontend applications.