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Part 132 of 355

๐ŸŽญ Import Types: Type-Only Imports

Master type-only imports to optimize bundle size, eliminate runtime dependencies, and create cleaner TypeScript architectures with zero-cost type imports ๐Ÿš€

๐Ÿš€Intermediate
20 min read

Prerequisites

  • Understanding of TypeScript type system and interfaces ๐Ÿ“
  • Knowledge of ES6 modules and import/export statements โšก
  • Familiarity with TypeScript compilation process ๐Ÿ’ป

What you'll learn

  • Master type-only import syntax and best practices ๐ŸŽฏ
  • Optimize bundle size by eliminating unnecessary runtime imports ๐Ÿ—๏ธ
  • Implement clean separation between types and values ๐Ÿ›
  • Create efficient type-only module architectures โœจ

๐ŸŽฏ Introduction

Welcome to the elegant world of type-only imports! ๐ŸŽญ If regular imports were like bringing both the script and the actors to a theater performance, then type-only imports are like bringing just the script - you get all the information you need for the show without the extra overhead of the physical actors taking up space!

Type-only imports are a powerful TypeScript feature that allows you to import types, interfaces, and type aliases without including any runtime code in your bundle. This creates cleaner architectures, smaller bundle sizes, and better separation of concerns between compile-time type checking and runtime behavior.

By the end of this tutorial, youโ€™ll be a type-only import expert, capable of creating optimized TypeScript architectures that maintain excellent type safety while minimizing runtime overhead. Letโ€™s explore the art of zero-cost type imports! ๐ŸŒŸ

๐Ÿ“š Understanding Type-Only Imports

๐Ÿค” What Are Type-Only Imports?

Type-only imports allow you to import type information without importing any runtime values. Theyโ€™re completely erased during compilation, leaving no trace in the final JavaScript output while providing full type checking during development.

// ๐ŸŒŸ Regular imports - include both types AND runtime values
import { UserService, User, UserRole } from './UserModule';

// This imports:
// - UserService (class/function - runtime value) โœ…
// - User (interface - type only) โœ…  
// - UserRole (enum/type - could be runtime or type) โ“

// โšก Type-only imports - ONLY types, zero runtime overhead
import type { User, UserRole, UserPermissions } from './UserModule';
import { UserService } from './UserModule'; // Only the runtime value

// ๐ŸŽฏ Mixed imports - both types and values in one statement
import { UserService, type User, type UserRole } from './UserModule';

// โœจ This clearly separates what's needed at runtime vs compile-time

// ๐Ÿ“ฆ Before type-only imports (bundle includes everything)
import { 
  UserInterface,     // Type only, but bundled anyway
  UserPermissions,   // Type only, but bundled anyway  
  UserService,       // Runtime value, needed in bundle
  validateUser,      // Runtime function, needed in bundle
  UserRole          // Could be enum (runtime) or type alias
} from './UserModule';

// ๐Ÿ“ฆ After type-only imports (optimized bundle)
import type { 
  UserInterface,     // Type only, completely erased
  UserPermissions,   // Type only, completely erased
  UserRole          // Type only, completely erased
} from './UserModule';

import { 
  UserService,       // Runtime value, included in bundle
  validateUser       // Runtime function, included in bundle
} from './UserModule';

// ๐ŸŽฎ Let's explore comprehensive type-only import patterns
console.log('๐ŸŽญ Type-Only Import Examples');

// ๐Ÿ“ Example module structure for demonstration:
// src/
//   โ”œโ”€โ”€ types/
//   โ”‚   โ”œโ”€โ”€ User.ts           // Pure type definitions
//   โ”‚   โ”œโ”€โ”€ Api.ts            // API type definitions  
//   โ”‚   โ””โ”€โ”€ Common.ts         // Shared type utilities
//   โ”œโ”€โ”€ services/
//   โ”‚   โ”œโ”€โ”€ UserService.ts    // Runtime service + types
//   โ”‚   โ”œโ”€โ”€ ApiService.ts     // Runtime service + types
//   โ”‚   โ””โ”€โ”€ ValidationService.ts
//   โ””โ”€โ”€ utils/
//       โ”œโ”€โ”€ typeGuards.ts     // Runtime type checking
//       โ””โ”€โ”€ validators.ts     // Runtime validation

// ๐ŸŽฏ Pure type-only module (types/User.ts)
export interface User {
  id: string;
  name: string;
  email: string;
  role: UserRole;
  permissions: UserPermissions[];
  metadata: UserMetadata;
}

export interface UserRole {
  id: string;
  name: string;
  level: number;
}

export interface UserPermissions {
  resource: string;
  actions: string[];
  conditions?: Record<string, any>;
}

export interface UserMetadata {
  createdAt: Date;
  updatedAt: Date;
  lastLogin?: Date;
  preferences: UserPreferences;
}

export interface UserPreferences {
  theme: 'light' | 'dark' | 'auto';
  language: string;
  notifications: NotificationSettings;
}

export interface NotificationSettings {
  email: boolean;
  push: boolean;
  sms: boolean;
  frequency: 'immediate' | 'daily' | 'weekly';
}

// ๐ŸŽฏ Type utilities for user operations
export type CreateUserRequest = Omit<User, 'id' | 'metadata'>;
export type UpdateUserRequest = Partial<Pick<User, 'name' | 'email' | 'role'>>;
export type UserResponse = User & { token?: string };
export type UserListResponse = {
  users: User[];
  total: number;
  page: number;
  limit: number;
};

// ๐Ÿ”ง Advanced type utilities
export type UserWithoutSensitiveData = Omit<User, 'permissions' | 'metadata'>;
export type UserRoleNames = UserRole['name'];
export type PermissionActions = UserPermissions['actions'][number];

// ๐Ÿ—๏ธ Type-only import analyzer class
class TypeOnlyImportAnalyzer {
  // ๐Ÿ“Š Track import usage statistics
  private importStats = {
    typeOnly: 0,
    valueOnly: 0,
    mixed: 0,
    total: 0
  };

  // ๐Ÿ“ Module dependency graph
  private dependencyGraph = new Map<string, {
    typeImports: Set<string>;
    valueImports: Set<string>;
    fromModules: Set<string>;
  }>();

  // ๐Ÿ” Analyze import statement
  analyzeImport(
    importStatement: string,
    fromModule: string,
    targetModule: string
  ): {
    type: 'type-only' | 'value-only' | 'mixed';
    typeImports: string[];
    valueImports: string[];
    optimizationSuggestions: string[];
  } {
    console.log(`๐Ÿ” Analyzing import: ${importStatement}`);

    const typeImports: string[] = [];
    const valueImports: string[] = [];
    const optimizationSuggestions: string[] = [];

    // ๐ŸŽฏ Parse import statement (simplified parsing)
    const isTypeOnlyImport = importStatement.includes('import type');
    const hasTypeKeyword = importStatement.includes('type ');

    // ๐Ÿ“ Extract imported names (simplified)
    const importMatch = importStatement.match(/import\s+(?:type\s+)?{([^}]+)}/);
    if (importMatch) {
      const imports = importMatch[1].split(',').map(imp => imp.trim());
      
      imports.forEach(imp => {
        if (imp.startsWith('type ')) {
          typeImports.push(imp.replace('type ', ''));
        } else if (isTypeOnlyImport) {
          typeImports.push(imp);
        } else {
          // ๐Ÿค” Could be either - needs analysis
          if (this.isKnownType(imp, targetModule)) {
            typeImports.push(imp);
            optimizationSuggestions.push(
              `Consider using 'type ${imp}' for type-only import`
            );
          } else {
            valueImports.push(imp);
          }
        }
      });
    }

    // ๐Ÿ“Š Update statistics
    let importType: 'type-only' | 'value-only' | 'mixed';
    if (typeImports.length > 0 && valueImports.length === 0) {
      importType = 'type-only';
      this.importStats.typeOnly++;
    } else if (valueImports.length > 0 && typeImports.length === 0) {
      importType = 'value-only';
      this.importStats.valueOnly++;
    } else {
      importType = 'mixed';
      this.importStats.mixed++;
    }

    this.importStats.total++;

    // ๐Ÿ—‚๏ธ Update dependency graph
    this.updateDependencyGraph(fromModule, targetModule, typeImports, valueImports);

    // ๐Ÿ’ก Generate optimization suggestions
    if (importType === 'mixed' && typeImports.length > 0) {
      optimizationSuggestions.push(
        'Consider separating type and value imports for better optimization'
      );
    }

    if (typeImports.length > valueImports.length && !isTypeOnlyImport) {
      optimizationSuggestions.push(
        'Most imports are types - consider using type-only import'
      );
    }

    console.log(`๐Ÿ“Š Import analysis complete: ${importType}`);
    
    return {
      type: importType,
      typeImports,
      valueImports,
      optimizationSuggestions
    };
  }

  // ๐Ÿ” Check if import is a known type
  private isKnownType(importName: string, module: string): boolean {
    // ๐ŸŽฏ Type detection heuristics
    const typePatterns = [
      /^[A-Z]\w*$/,                    // PascalCase (likely interface/type)
      /Interface$/,                    // Ends with Interface
      /Type$/,                         // Ends with Type
      /Props$/,                        // React props
      /Config$/,                       // Configuration types
      /Options$/,                      // Option types
      /Response$/,                     // API response types
      /Request$/                       // API request types
    ];

    // ๐Ÿ“š Known type modules
    const typeModules = [
      './types/',
      './interfaces/',
      './models/',
      '@types/'
    ];

    // ๐Ÿ” Check patterns
    if (typePatterns.some(pattern => pattern.test(importName))) {
      return true;
    }

    // ๐Ÿ” Check if from type-only module
    if (typeModules.some(typeModule => module.includes(typeModule))) {
      return true;
    }

    return false;
  }

  // ๐Ÿ—‚๏ธ Update dependency graph
  private updateDependencyGraph(
    fromModule: string,
    targetModule: string,
    typeImports: string[],
    valueImports: string[]
  ): void {
    if (!this.dependencyGraph.has(fromModule)) {
      this.dependencyGraph.set(fromModule, {
        typeImports: new Set(),
        valueImports: new Set(),
        fromModules: new Set()
      });
    }

    const moduleData = this.dependencyGraph.get(fromModule)!;
    
    typeImports.forEach(imp => moduleData.typeImports.add(imp));
    valueImports.forEach(imp => moduleData.valueImports.add(imp));
    moduleData.fromModules.add(targetModule);
  }

  // ๐Ÿ“Š Generate optimization report
  generateOptimizationReport(): {
    summary: string;
    statistics: typeof this.importStats;
    recommendations: string[];
    potentialSavings: number;
  } {
    const recommendations: string[] = [];
    let potentialSavings = 0;

    // ๐Ÿ“ˆ Analyze statistics
    const mixedImportRatio = this.importStats.mixed / this.importStats.total;
    const typeImportRatio = this.importStats.typeOnly / this.importStats.total;

    if (mixedImportRatio > 0.3) {
      recommendations.push(
        'High number of mixed imports detected - consider separating type and value imports'
      );
      potentialSavings += this.importStats.mixed * 0.1; // Estimated 10% savings per mixed import
    }

    if (typeImportRatio < 0.5) {
      recommendations.push(
        'Low usage of type-only imports - review imports for optimization opportunities'
      );
    }

    // ๐Ÿ” Analyze dependency graph
    for (const [module, data] of this.dependencyGraph) {
      const typeCount = data.typeImports.size;
      const valueCount = data.valueImports.size;
      
      if (typeCount > valueCount * 2) {
        recommendations.push(
          `Module ${module} imports mostly types - consider type-only imports`
        );
        potentialSavings += typeCount * 0.05; // Estimated savings
      }
    }

    const summary = `Analyzed ${this.importStats.total} imports: ${this.importStats.typeOnly} type-only, ${this.importStats.valueOnly} value-only, ${this.importStats.mixed} mixed`;

    return {
      summary,
      statistics: { ...this.importStats },
      recommendations,
      potentialSavings: Math.round(potentialSavings * 100) / 100
    };
  }

  // ๐Ÿ—๏ธ Generate optimized import suggestions
  generateOptimizedImports(
    fromModule: string
  ): {
    original: string[];
    optimized: string[];
    explanation: string[];
  } {
    const moduleData = this.dependencyGraph.get(fromModule);
    if (!moduleData) {
      return { original: [], optimized: [], explanation: [] };
    }

    const original: string[] = [];
    const optimized: string[] = [];
    const explanation: string[] = [];

    // ๐ŸŽฏ Group by target module
    const moduleGroups = new Map<string, {
      types: string[];
      values: string[];
    }>();

    // ๐Ÿ“Š Organize imports by target module
    for (const targetModule of moduleData.fromModules) {
      if (!moduleGroups.has(targetModule)) {
        moduleGroups.set(targetModule, { types: [], values: [] });
      }
    }

    // ๐Ÿ”ง Generate optimized import statements
    for (const [targetModule, imports] of moduleGroups) {
      const { types, values } = imports;

      if (types.length > 0 && values.length > 0) {
        // Mixed import - separate them
        original.push(`import { ${[...types, ...values].join(', ')} } from '${targetModule}';`);
        
        optimized.push(`import type { ${types.join(', ')} } from '${targetModule}';`);
        optimized.push(`import { ${values.join(', ')} } from '${targetModule}';`);
        
        explanation.push(`Separated types and values for ${targetModule} to optimize bundle size`);
        
      } else if (types.length > 0) {
        // Type-only import
        original.push(`import { ${types.join(', ')} } from '${targetModule}';`);
        optimized.push(`import type { ${types.join(', ')} } from '${targetModule}';`);
        
        explanation.push(`Converted to type-only import for ${targetModule}`);
        
      } else if (values.length > 0) {
        // Value-only import - already optimized
        const statement = `import { ${values.join(', ')} } from '${targetModule}';`;
        original.push(statement);
        optimized.push(statement);
        
        explanation.push(`Value-only import for ${targetModule} is already optimized`);
      }
    }

    return { original, optimized, explanation };
  }

  // ๐Ÿงน Reset analyzer
  reset(): void {
    this.importStats = {
      typeOnly: 0,
      valueOnly: 0,
      mixed: 0,
      total: 0
    };
    this.dependencyGraph.clear();
    
    console.log('๐Ÿงน Import analyzer reset');
  }
}

// ๐ŸŽฎ Usage examples
const typeImportDemo = (): void => {
  const analyzer = new TypeOnlyImportAnalyzer();

  // ๐Ÿ” Analyze different import patterns
  const imports = [
    "import { User, UserService, validateUser } from './UserModule';",
    "import type { User, UserRole } from './types/User';",
    "import { UserService, type User, type UserRole } from './UserModule';",
    "import type { ApiResponse } from './types/Api';",
    "import { createUser, type CreateUserRequest } from './UserService';"
  ];

  imports.forEach((importStatement, index) => {
    const analysis = analyzer.analyzeImport(
      importStatement,
      `./module${index}`,
      './UserModule'
    );
    
    console.log(`๐Ÿ“Š Analysis ${index + 1}:`, analysis);
  });

  // ๐Ÿ“Š Generate optimization report
  const report = analyzer.generateOptimizationReport();
  console.log('๐Ÿ“Š Optimization Report:', report);

  // ๐Ÿ—๏ธ Generate optimized imports
  const optimizedImports = analyzer.generateOptimizedImports('./module0');
  console.log('๐Ÿ—๏ธ Optimized Imports:', optimizedImports);
};

// ๐ŸŽฏ Advanced type-only import patterns
interface TypeImportConfig {
  // ๐Ÿ“‚ Module organization
  typeModules: string[];           // Pure type modules
  mixedModules: string[];          // Modules with types and values
  valueModules: string[];          // Pure value modules
  
  // ๐Ÿ”ง Import strategies
  preferTypeOnly: boolean;         // Prefer type-only imports when possible
  separateTypeImports: boolean;    // Separate type and value imports
  groupImportsByModule: boolean;   // Group imports from same module
  
  // ๐Ÿ“Š Bundle optimization
  analyzeBundleImpact: boolean;    // Analyze bundle size impact
  generateSourceMaps: boolean;     // Generate source maps for debugging
  trackUnusedTypes: boolean;       // Track unused type imports
}

// ๐Ÿ—๏ธ Smart type import manager
class SmartTypeImportManager {
  private config: TypeImportConfig;
  private usageTracker = new Map<string, {
    imported: number;
    used: number;
    lastUsed: Date;
  }>();

  constructor(config: TypeImportConfig) {
    this.config = config;
  }

  // ๐ŸŽฏ Optimize import statement
  optimizeImportStatement(
    importStatement: string,
    fromModule: string,
    targetModule: string
  ): {
    optimized: string[];
    bundleSizeReduction: number;
    recommendations: string[];
  } {
    console.log(`๐ŸŽฏ Optimizing import: ${importStatement}`);

    const recommendations: string[] = [];
    let bundleSizeReduction = 0;

    // ๐Ÿ” Parse import statement
    const { types, values, isTypeOnly, isMixed } = this.parseImportStatement(importStatement);

    const optimized: string[] = [];

    if (isMixed && this.config.separateTypeImports) {
      // ๐Ÿ“ Separate type and value imports
      if (types.length > 0) {
        optimized.push(`import type { ${types.join(', ')} } from '${targetModule}';`);
        bundleSizeReduction += types.length * 0.1; // Estimated reduction
      }
      
      if (values.length > 0) {
        optimized.push(`import { ${values.join(', ')} } from '${targetModule}';`);
      }
      
      recommendations.push('Separated type and value imports for better tree shaking');
      
    } else if (!isTypeOnly && types.length > 0 && this.config.preferTypeOnly) {
      // ๐Ÿ”„ Convert to type-only if all imports are types
      if (values.length === 0) {
        optimized.push(`import type { ${types.join(', ')} } from '${targetModule}';`);
        bundleSizeReduction += types.length * 0.15;
        recommendations.push('Converted to type-only import');
      } else {
        optimized.push(importStatement);
        recommendations.push('Mixed import detected - consider separating types and values');
      }
      
    } else {
      // โœ… Already optimized
      optimized.push(importStatement);
      recommendations.push('Import statement is already optimized');
    }

    // ๐Ÿ“Š Track usage
    this.trackImportUsage(types.concat(values), targetModule);

    return {
      optimized,
      bundleSizeReduction: Math.round(bundleSizeReduction * 100) / 100,
      recommendations
    };
  }

  // ๐Ÿ” Parse import statement
  private parseImportStatement(importStatement: string): {
    types: string[];
    values: string[];
    isTypeOnly: boolean;
    isMixed: boolean;
  } {
    const types: string[] = [];
    const values: string[] = [];
    
    const isTypeOnly = importStatement.includes('import type');
    const hasTypeKeyword = importStatement.includes('type ');

    // ๐Ÿ“ Simple parsing (in real implementation, use proper AST parsing)
    const importMatch = importStatement.match(/import\s+(?:type\s+)?{([^}]+)}/);
    
    if (importMatch) {
      const imports = importMatch[1].split(',').map(imp => imp.trim());
      
      imports.forEach(imp => {
        if (imp.startsWith('type ')) {
          types.push(imp.replace('type ', ''));
        } else if (isTypeOnly) {
          types.push(imp);
        } else {
          // ๐Ÿค” Heuristic: assume PascalCase imports are types
          if (/^[A-Z]/.test(imp) && !imp.includes('Service') && !imp.includes('Manager')) {
            types.push(imp);
          } else {
            values.push(imp);
          }
        }
      });
    }

    const isMixed = types.length > 0 && values.length > 0;

    return { types, values, isTypeOnly, isMixed };
  }

  // ๐Ÿ“Š Track import usage
  private trackImportUsage(imports: string[], fromModule: string): void {
    if (!this.config.trackUnusedTypes) return;

    imports.forEach(imp => {
      const key = `${fromModule}:${imp}`;
      const current = this.usageTracker.get(key) || { imported: 0, used: 0, lastUsed: new Date() };
      
      current.imported++;
      this.usageTracker.set(key, current);
    });
  }

  // ๐Ÿ—๏ธ Generate module organization suggestions
  generateModuleOrganizationSuggestions(): {
    typeOnlyModules: string[];
    mixedModules: string[];
    organizationTips: string[];
  } {
    const typeOnlyModules: string[] = [];
    const mixedModules: string[] = [];
    const organizationTips: string[] = [];

    // ๐Ÿ“Š Analyze current module usage
    const moduleStats = new Map<string, { types: number; values: number }>();

    this.usageTracker.forEach((usage, key) => {
      const [module, imp] = key.split(':');
      const stats = moduleStats.get(module) || { types: 0, values: 0 };
      
      // ๐Ÿค” Heuristic classification
      if (/^[A-Z]/.test(imp) || imp.includes('Type') || imp.includes('Interface')) {
        stats.types++;
      } else {
        stats.values++;
      }
      
      moduleStats.set(module, stats);
    });

    // ๐Ÿ—๏ธ Generate suggestions
    moduleStats.forEach((stats, module) => {
      if (stats.types > 0 && stats.values === 0) {
        typeOnlyModules.push(module);
      } else if (stats.types > 0 && stats.values > 0) {
        mixedModules.push(module);
        
        if (stats.types > stats.values * 2) {
          organizationTips.push(
            `Consider splitting ${module} - it exports mostly types`
          );
        }
      }
    });

    // ๐Ÿ“ General organization tips
    organizationTips.push(
      'Create dedicated type modules for better organization',
      'Use barrel exports to organize type exports',
      'Separate types from runtime code when possible'
    );

    return {
      typeOnlyModules,
      mixedModules,
      organizationTips
    };
  }

  // ๐Ÿ” Find unused type imports
  findUnusedTypeImports(): Array<{
    module: string;
    import: string;
    timeSinceLastUse: number;
  }> {
    const unused: Array<any> = [];
    const now = new Date();

    this.usageTracker.forEach((usage, key) => {
      if (usage.used === 0) {
        const [module, imp] = key.split(':');
        const timeSinceLastUse = now.getTime() - usage.lastUsed.getTime();
        
        unused.push({
          module,
          import: imp,
          timeSinceLastUse: Math.floor(timeSinceLastUse / (1000 * 60 * 60 * 24)) // Days
        });
      }
    });

    return unused.sort((a, b) => b.timeSinceLastUse - a.timeSinceLastUse);
  }

  // ๐Ÿ“Š Generate comprehensive report
  generateComprehensiveReport(): {
    optimizationOpportunities: number;
    bundleSizeReduction: number;
    unusedImports: number;
    recommendations: string[];
  } {
    let optimizationOpportunities = 0;
    let bundleSizeReduction = 0;
    let unusedImports = 0;
    const recommendations: string[] = [];

    // ๐Ÿ“Š Analyze usage patterns
    const moduleStats = new Map<string, { types: number; values: number; mixed: number }>();

    this.usageTracker.forEach((usage, key) => {
      const [module] = key.split(':');
      const stats = moduleStats.get(module) || { types: 0, values: 0, mixed: 0 };
      
      if (usage.used === 0) {
        unusedImports++;
        bundleSizeReduction += 0.05; // Estimated savings from removing unused import
      }
      
      moduleStats.set(module, stats);
    });

    // ๐ŸŽฏ Count optimization opportunities
    moduleStats.forEach((stats, module) => {
      if (stats.types > 5 && stats.values === 0) {
        optimizationOpportunities++;
        recommendations.push(`${module} can be converted to type-only imports`);
      }
      
      if (stats.mixed > 3) {
        optimizationOpportunities++;
        recommendations.push(`${module} has mixed imports that can be separated`);
      }
    });

    // ๐Ÿ’ก General recommendations
    if (unusedImports > 0) {
      recommendations.push(`Remove ${unusedImports} unused type imports`);
    }

    if (optimizationOpportunities > 0) {
      recommendations.push('Implement type-only imports for better performance');
    }

    return {
      optimizationOpportunities,
      bundleSizeReduction: Math.round(bundleSizeReduction * 100) / 100,
      unusedImports,
      recommendations
    };
  }
}

// ๐ŸŽฎ Advanced usage example
const advancedTypeImportDemo = (): void => {
  const config: TypeImportConfig = {
    typeModules: ['./types/', './interfaces/', './models/'],
    mixedModules: ['./services/', './utils/'],
    valueModules: ['./constants/', './config/'],
    preferTypeOnly: true,
    separateTypeImports: true,
    groupImportsByModule: true,
    analyzeBundleImpact: true,
    generateSourceMaps: true,
    trackUnusedTypes: true
  };

  const manager = new SmartTypeImportManager(config);

  // ๐ŸŽฏ Optimize various import statements
  const testImports = [
    "import { User, UserService, validateUser } from './services/UserService';",
    "import { ApiResponse, ApiError, fetchData } from './utils/api';",
    "import { Theme, Config, initializeApp } from './config/app';"
  ];

  testImports.forEach((importStatement, index) => {
    const result = manager.optimizeImportStatement(
      importStatement,
      `./component${index}`,
      './services/UserService'
    );
    
    console.log(`๐ŸŽฏ Optimization ${index + 1}:`, result);
  });

  // ๐Ÿ—๏ธ Get organization suggestions
  const suggestions = manager.generateModuleOrganizationSuggestions();
  console.log('๐Ÿ—๏ธ Organization Suggestions:', suggestions);

  // ๐Ÿ” Find unused imports
  const unusedImports = manager.findUnusedTypeImports();
  console.log('๐Ÿ” Unused Imports:', unusedImports);

  // ๐Ÿ“Š Generate comprehensive report
  const report = manager.generateComprehensiveReport();
  console.log('๐Ÿ“Š Comprehensive Report:', report);
};

// ๐ŸŽฏ Execute demonstrations
typeImportDemo();
advancedTypeImportDemo();

๐Ÿ’ก Common Type-Only Import Patterns

Letโ€™s explore the most effective patterns for using type-only imports:

// ๐ŸŒŸ Pattern 1: Pure Type Modules
// Organize types in dedicated modules for clean separation

// ๐Ÿ“ types/User.ts - Pure type module
export interface User {
  id: string;
  name: string;
  email: string;
}

export interface UserPreferences {
  theme: 'light' | 'dark';
  language: string;
}

export type UserRole = 'admin' | 'user' | 'moderator';
export type UserStatus = 'active' | 'inactive' | 'pending';

// ๐Ÿ“ services/UserService.ts - Mixed module
import type { User, UserPreferences, UserRole } from '../types/User';

export class UserService {
  async getUser(id: string): Promise<User> {
    // Implementation
    return {} as User;
  }

  async updatePreferences(
    userId: string, 
    preferences: UserPreferences
  ): Promise<void> {
    // Implementation
  }

  async assignRole(userId: string, role: UserRole): Promise<void> {
    // Implementation
  }
}

export const validateUser = (user: User): boolean => {
  return user.id.length > 0 && user.email.includes('@');
};

// ๐Ÿ“ components/UserProfile.tsx - Consumer module
import type { User, UserPreferences } from '../types/User';
import { UserService, validateUser } from '../services/UserService';

// Clean separation: types imported as types, values as values

// ๐ŸŒŸ Pattern 2: Conditional Type-Only Imports
// Import types only when needed for specific features

// ๐Ÿ“ features/AdminPanel.tsx
import type { User } from '../types/User';

// Conditionally import admin-specific types
let AdminUser: typeof import('../types/Admin').AdminUser;
let AdminPermissions: typeof import('../types/Admin').AdminPermissions;

const AdminPanel: React.FC = () => {
  // Only load admin types if user is admin
  const loadAdminTypes = async () => {
    if (currentUser.role === 'admin') {
      const adminTypes = await import('../types/Admin');
      AdminUser = adminTypes.AdminUser;
      AdminPermissions = adminTypes.AdminPermissions;
    }
  };

  return <div>Admin Panel</div>;
};

// ๐ŸŒŸ Pattern 3: Generic Type Utilities
// Create reusable type-only utilities

// ๐Ÿ“ types/ApiTypes.ts - Generic API type utilities
export interface ApiResponse<T> {
  data: T;
  status: number;
  message: string;
}

export interface ApiError {
  code: string;
  message: string;
  details?: Record<string, any>;
}

export interface PaginatedResponse<T> {
  items: T[];
  totalCount: number;
  page: number;
  pageSize: number;
}

// Type utilities
export type ApiResult<T> = ApiResponse<T> | ApiError;
export type PaginatedApiResponse<T> = ApiResponse<PaginatedResponse<T>>;

// ๐Ÿ“ services/ApiService.ts - Service using type utilities
import type { 
  ApiResponse, 
  ApiError, 
  PaginatedResponse,
  ApiResult 
} from '../types/ApiTypes';

export class ApiService {
  async get<T>(url: string): Promise<ApiResult<T>> {
    // Implementation
    return {} as ApiResult<T>;
  }

  async getPaginated<T>(
    url: string, 
    page: number, 
    pageSize: number
  ): Promise<ApiResult<PaginatedResponse<T>>> {
    // Implementation
    return {} as ApiResult<PaginatedResponse<T>>;
  }
}

// ๐ŸŒŸ Pattern 4: Barrel Exports with Type Separation
// Organize exports to clearly separate types and values

// ๐Ÿ“ index.ts - Main barrel export
// Type-only exports
export type {
  User,
  UserPreferences,
  UserRole,
  UserStatus
} from './types/User';

export type {
  ApiResponse,
  ApiError,
  PaginatedResponse
} from './types/ApiTypes';

// Value exports
export { UserService, validateUser } from './services/UserService';
export { ApiService } from './services/ApiService';

// ๐Ÿ“ Alternative organized barrel export
// Group by feature
export type * as UserTypes from './types/User';
export type * as ApiTypes from './types/ApiTypes';

export * as UserServices from './services/UserService';
export * as ApiServices from './services/ApiService';

// Usage with organized imports
import type { UserTypes, ApiTypes } from './index';
import { UserServices, ApiServices } from './index';

// ๐ŸŒŸ Pattern 5: Framework-Specific Type Patterns
// Optimize for specific frameworks and libraries

// ๐Ÿ“ React-specific type patterns
import type { FC, PropsWithChildren, ComponentProps } from 'react';
import type { User } from '../types/User';

// Component props with type-only imports
interface UserCardProps {
  user: User;
  onClick?: (user: User) => void;
}

export const UserCard: FC<UserCardProps> = ({ user, onClick }) => {
  return (
    <div onClick={() => onClick?.(user)}>
      {user.name}
    </div>
  );
};

// Higher-order component types
export type WithUserProps<T = {}> = T & {
  user: User;
};

export const withUser = <P extends {}>(
  Component: FC<P>
): FC<WithUserProps<P>> => {
  return (props) => {
    // Implementation
    return <Component {...props} />;
  };
};

// ๐Ÿ“ Node.js-specific type patterns
import type { Request, Response, NextFunction } from 'express';
import type { User, UserRole } from '../types/User';

// Middleware types
export type AuthenticatedRequest = Request & {
  user: User;
};

export type RoleCheckMiddleware = (
  roles: UserRole[]
) => (req: Request, res: Response, next: NextFunction) => void;

// API handler types
export type ApiHandler<T = any> = (
  req: AuthenticatedRequest,
  res: Response
) => Promise<T>;

// ๐ŸŒŸ Pattern 6: Build-Time Type Optimization
// Optimize types for different build environments

// ๐Ÿ“ types/BuildOptimized.ts
// Development-only types (stripped in production)
export interface DebugInfo {
  timestamp: number;
  sourceLocation: string;
  stackTrace: string[];
}

export interface DevToolsAPI {
  log: (message: string, data?: any) => void;
  inspect: (object: any) => void;
}

// Production-optimized types
export interface ProductionConfig {
  apiUrl: string;
  cdnUrl: string;
  features: string[];
}

// Conditional type exports based on environment
export type AppConfig = typeof process.env.NODE_ENV extends 'development'
  ? ProductionConfig & { debug: DebugInfo; devTools: DevToolsAPI }
  : ProductionConfig;

// ๐Ÿ“ config/environment.ts
import type { AppConfig } from '../types/BuildOptimized';

// Only import debug types in development
let DebugInfo: typeof import('../types/BuildOptimized').DebugInfo;
let DevToolsAPI: typeof import('../types/BuildOptimized').DevToolsAPI;

if (process.env.NODE_ENV === 'development') {
  // These imports are tree-shaken in production
  import('../types/BuildOptimized').then(module => {
    DebugInfo = module.DebugInfo;
    DevToolsAPI = module.DevToolsAPI;
  });
}

export const createConfig = (): AppConfig => {
  const baseConfig = {
    apiUrl: process.env.API_URL || '',
    cdnUrl: process.env.CDN_URL || '',
    features: []
  };

  if (process.env.NODE_ENV === 'development') {
    return {
      ...baseConfig,
      debug: {
        timestamp: Date.now(),
        sourceLocation: __filename,
        stackTrace: []
      },
      devTools: {
        log: console.log,
        inspect: console.dir
      }
    } as AppConfig;
  }

  return baseConfig as AppConfig;
};

// ๐ŸŒŸ Pattern 7: Micro-Frontend Type Sharing
// Share types across micro-frontends efficiently

// ๐Ÿ“ shared-types/package.json
{
  "name": "@company/shared-types",
  "version": "1.0.0",
  "types": "./dist/index.d.ts",
  "sideEffects": false  // Important for tree-shaking
}

// ๐Ÿ“ shared-types/src/index.ts
// Only export types - no runtime code
export type { User, UserRole, UserPreferences } from './User';
export type { ApiResponse, ApiError } from './Api';
export type { Theme, Config } from './Common';

// Type utilities
export type * as UserTypes from './User';
export type * as ApiTypes from './Api';
export type * as CommonTypes from './Common';

// ๐Ÿ“ micro-frontend-a/src/components/UserList.tsx
import type { User } from '@company/shared-types';
// No runtime dependencies on shared package!

// ๐Ÿ“ micro-frontend-b/src/services/UserService.ts
import type { User, ApiResponse } from '@company/shared-types';
// Consistent types across micro-frontends

// ๐ŸŒŸ Pattern 8: Library Type Definitions
// Create efficient type definitions for libraries

// ๐Ÿ“ my-library/types/index.ts
// Library public API types
export interface LibraryConfig {
  apiKey: string;
  baseUrl?: string;
  timeout?: number;
}

export interface LibraryInstance {
  configure: (config: LibraryConfig) => void;
  request: <T>(options: RequestOptions) => Promise<T>;
}

// Internal types (not exported)
interface InternalState {
  initialized: boolean;
  config: LibraryConfig;
}

// Type guards for runtime type checking
export const isLibraryConfig = (obj: any): obj is LibraryConfig => {
  return obj && typeof obj.apiKey === 'string';
};

// ๐Ÿ“ my-library/src/index.ts
import type { LibraryConfig, LibraryInstance } from '../types';

export type { LibraryConfig, LibraryInstance } from '../types';

export const createLibrary = (config: LibraryConfig): LibraryInstance => {
  // Implementation
  return {} as LibraryInstance;
};

// Users only get type imports, minimal runtime footprint
// Usage:
// import type { LibraryConfig } from 'my-library';
// import { createLibrary } from 'my-library';

๐ŸŽ‰ Conclusion

Congratulations! Youโ€™ve mastered the art of type-only imports! ๐ŸŽญ

๐ŸŽฏ What Youโ€™ve Learned

  • ๐ŸŽญ Type-Only Syntax: Using import type and type keywords effectively
  • ๐Ÿ“ฆ Bundle Optimization: Eliminating unnecessary runtime imports for smaller bundles
  • ๐Ÿ—๏ธ Clean Architecture: Separating compile-time types from runtime values
  • ๐Ÿ”ง Advanced Patterns: Sophisticated strategies for organizing and optimizing type imports
  • ๐Ÿ“Š Performance Analysis: Tools and techniques for measuring and improving import efficiency

๐Ÿš€ Key Benefits

  • ๐Ÿ“‰ Smaller Bundles: Eliminate unused runtime code from your bundles
  • โšก Faster Builds: Reduce compilation overhead with optimized imports
  • ๐ŸŽฏ Better Organization: Clear separation between types and runtime code
  • ๐Ÿ”ง Easier Refactoring: Type-only imports make refactoring safer and more predictable
  • ๐Ÿ“ฆ Library Optimization: Create more efficient libraries with minimal runtime footprint

๐Ÿ”ฅ Best Practices Recap

  1. ๐ŸŽฏ Separate Types and Values: Use type-only imports for types, regular imports for values
  2. ๐Ÿ“ Organize by Purpose: Create dedicated type modules for better organization
  3. ๐Ÿ”ง Leverage Tools: Use analyzers to find optimization opportunities
  4. ๐Ÿ“Š Monitor Bundle Size: Track the impact of your import optimizations
  5. ๐ŸŽญ Think at Design Time: Plan your module architecture with type imports in mind

Youโ€™re now equipped to create highly optimized TypeScript applications with clean, efficient module architectures that maximize performance while maintaining excellent type safety! ๐ŸŒŸ

Happy coding, and may your types always be imported exactly when needed! ๐ŸŽญโœจ