Version compatibility handling

In component development specifications, version compatibility handling is a critical aspect of ensuring system stability and maintainability. A reasonable version management strategy can reduce risks associated with upgrades while ensuring seamless integration of new and legacy features.

Version Number Specification

Adopting Semantic Versioning (SemVer) is an industry-standard practice, with the format MAJOR.MINOR.PATCH:

// Example version number
const version = {
  major: 2,  // Incompatible API changes
  minor: 1,  // Backward-compatible feature additions
  patch: 0   // Backward-compatible bug fixes
};

Special attention is required for MAJOR version changes:

• Removal or modification of public APIs
• Changes to core functionality
• Major dependency upgrades

Backward Compatibility Implementation

Interface Adaptation Layer

// Example of legacy and new API adaptation
class APIVersionAdapter {
  static getData(params: NewParamsType): LegacyResultType {
    const newResult = NewAPI.getData(params);
    return {
      old_format_data: newResult.dataList,
      status: newResult.code === 200 ? 'success' : 'fail'
    };
  }
}

Feature Flag Control

// Feature flag configuration
const featureFlags = {
  useNewComponent: localStorage.getItem('FEATURE_2023') === 'true',
  legacyFallback: true
};

function renderComponent() {
  return featureFlags.useNewComponent ? 
    <NewComponent /> : 
    <LegacyComponent />;
}

Multi-Version Coexistence Strategy

Dynamic Loading Mechanism

// Dynamically load components by version
async function loadComponent(version) {
  try {
    const module = await import(`./components/v${version}/Main.js`);
    return module.default;
  } catch (e) {
    console.warn(`Version ${version} not found, falling back`);
    return await import('./components/v1/Main.js');
  }
}

CSS Namespace Isolation

// Style isolation for different versions
.v2-component {
  .button {
    // v2-specific styles
  }
}

.v1-component {
  .button {
    // v1 legacy styles
  }
}

Dependency Management Practices

peerDependencies Configuration

{
  "peerDependencies": {
    "react": ">=16.8.0 <18.0.0",
    "react-dom": ">=16.8.0 <18.0.0"
  }
}

Version Detection Warning

// Runtime version check
if (React.version.startsWith('15.')) {
  console.warn(
    'Deprecated React version detected, please upgrade to v16+'
  );
}

Deprecation Process Management

Gradual Deprecation Plan

// Phased deprecation of functions
function deprecatedMethod() {
  console.warn('This method will be removed in v3.0');
  return legacyImplementation();
}

// Deprecation schedule configuration
const deprecationSchedule = {
  'utils/old.js': {
    since: '2.1.0',
    removeIn: '3.0.0',
    alternative: 'utils/new.js'
  }
};

Testing and Validation System

Version Matrix Testing

# Example CI test configuration
test_matrix:
  node: ["12.x", "14.x", "16.x"]
  react: ["16.8", "17.0", "18.0"]
  browser: ["chrome-latest", "firefox-latest"]

Type Definition Compatibility

// Type compatibility check
type IsCompatible<T, U> = T extends U ? true : false;

type CheckParams = IsCompatible<LegacyParams, NewParams>;
// => Returns true if types are compatible

Documentation Standards

Version change documentation should include:

1. Description of change impact
2. Migration guide (with code examples)
3. Timeline planning
4. Emergency rollback plan

## [2.2.0] - 2023-05-15

### Breaking Changes
- `config.set()` method signature change:
  ```diff
  - set(key: string, value: any)
  + set(options: { key: string; value: any; persist?: boolean })

Migration Guide

1. Replace all set calls:

   // Old syntax
   config.set('theme', 'dark');
   
   // New syntax
   config.set({ key: 'theme', value: 'dark' });
   

## Error Monitoring and Statistics

Implement version usage tracking:

```javascript
// Version usage statistics reporting
window.addEventListener('load', () => {
  navigator.sendBeacon('/analytics', JSON.stringify({
    componentVersion: window.__COMPONENT_VERSION,
    userAgent: navigator.userAgent
  }));
});

Automation Tool Integration

Version Migration Scripts

// Example codemod transformation
module.exports = function transformer(file, api) {
  const j = api.jscodeshift;
  
  return j(file.source)
    .find(j.CallExpression, {
      callee: { property: { name: 'set' } }
    })
    .replaceWith(path => {
      // Automatically transform legacy and new API calls
    })
    .toSource();
};

Dependency Version Checking

# Using npm-check-updates
ncu --dep dev,prod --upgrade

Canary Release Control

Implement phased release strategy:

// User ID-based canary release
function shouldEnableNewVersion(userId) {
  const hash = hashCode(userId);
  return hash % 100 < 10; // 10% traffic
}

Rollback Emergency Plan

Prepare detailed rollback checklist:

1. Database migration rollback scripts
2. Static resource version fallback
3. Configuration restoration mechanism
4. Client cache clearance plan

# Example rollback command
git revert v2.3.0
npm run rollback -- --target=2.2.5