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# General Configurations
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Standard TypeScript configurations for common development patterns and strictness levels. These configurations provide foundational settings that can be used across different environments.
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## Capabilities
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### Recommended Configuration
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The community-recommended baseline TypeScript configuration that provides a balanced set of compiler options suitable for most projects.
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```typescript { .api }
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interface RecommendedConfiguration {
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  /** Configuration type */
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  type: "Community Recommended";
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  /** Package name */
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  package: "@tsconfig/recommended";
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  /** Configuration */
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  config: {
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    $schema: "https://json.schemastore.org/tsconfig";
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    display: "Recommended";
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    compilerOptions: {
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      target: "es2016";
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      module: "commonjs";
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      esModuleInterop: true;
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      forceConsistentCasingInFileNames: true;
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      strict: true;
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      skipLibCheck: true;
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    };
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  };
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}
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```
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**Installation:**
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```bash
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npm install --save-dev @tsconfig/recommended
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```
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**Usage:**
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```json
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{
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  "extends": "@tsconfig/recommended/tsconfig.json"
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}
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```
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**Key Features:**
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- **ES2016 Target**: Modern JavaScript features with broad compatibility
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- **CommonJS Modules**: Standard Node.js module system
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- **Strict Mode**: Enabled for type safety
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- **ES Module Interop**: Seamless integration with ES modules
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- **Skip Lib Check**: Faster compilation by skipping declaration file checks
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### Strictest Configuration
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Maximum strictness TypeScript configuration that enables all possible type checking and code quality options.
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```typescript { .api }
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interface StrictestConfiguration {
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  /** Configuration type */
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  type: "Maximum Strictness";
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  /** Package name */
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  package: "@tsconfig/strictest";
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  /** Configuration */
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  config: {
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    $schema: "https://json.schemastore.org/tsconfig";
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    display: "Strictest";
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    _version: "2.0.0";
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    compilerOptions: {
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      strict: true;
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      allowUnusedLabels: false;
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      allowUnreachableCode: false;
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      exactOptionalPropertyTypes: true;
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      noFallthroughCasesInSwitch: true;
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      noImplicitOverride: true;
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      noImplicitReturns: true;
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      noPropertyAccessFromIndexSignature: true;
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      noUncheckedIndexedAccess: true;
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      noUnusedLocals: true;
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      noUnusedParameters: true;
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      isolatedModules: true;
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      checkJs: true;
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      esModuleInterop: true;
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      skipLibCheck: true;
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    };
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  };
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}
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```
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**Installation:**
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```bash
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npm install --save-dev @tsconfig/strictest
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```
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**Usage:**
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```json
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{
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  "extends": "@tsconfig/strictest/tsconfig.json"
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}
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```
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**Key Features:**
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- **Maximum Type Safety**: All strict checking options enabled
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- **Code Quality Enforcement**: Prevents unused variables and unreachable code
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- **Exact Optional Properties**: Strict handling of optional properties
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- **Implicit Return Checking**: Ensures all code paths return values
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- **Index Signature Safety**: Prevents unsafe property access
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- **JavaScript Checking**: Type checking for JavaScript files
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## Configuration Comparison
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Understanding the differences between recommended and strictest configurations:
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```typescript { .api }
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interface ConfigurationComparison {
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  /** Recommended vs Strictest */
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  comparison: {
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    recommended: {
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      purpose: "Balanced development experience";
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      strictness: "moderate";
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      features: [
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        "Basic strict mode",
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        "ES module interop",
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        "Consistent casing",
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        "Skip lib check"
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      ];
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      suitableFor: [
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        "New projects",
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        "Learning TypeScript",
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        "Quick prototyping",
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        "Legacy code migration"
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      ];
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    };
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    strictest: {
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      purpose: "Maximum code quality and safety";
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      strictness: "maximum";
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      features: [
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        "All strict options",
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        "Unused code detection",
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        "Unreachable code prevention",
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        "Exact optional properties",
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        "Index signature safety",
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        "JavaScript type checking"
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      ];
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      suitableFor: [
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        "Production applications",
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        "Team development",
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        "Long-term maintenance",
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        "Critical systems"
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      ];
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    };
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  };
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}
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```
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## Strictness Levels
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Different levels of TypeScript strictness and their implications:
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```typescript { .api }
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interface StrictnessLevels {
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  /** Basic strictness (recommended) */
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  basic: {
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    options: ["strict"];
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    impact: "Enables fundamental type checking";
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    benefits: ["Type safety", "Better IntelliSense", "Runtime error prevention"];
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    drawbacks: ["Some learning curve", "Potential legacy code issues"];
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  };
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  /** Enhanced strictness */
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  enhanced: {
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    options: [
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      "strict",
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      "noImplicitReturns",
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      "noFallthroughCasesInSwitch",
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      "noUnusedLocals",
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      "noUnusedParameters"
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    ];
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    impact: "Adds code quality enforcement";
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    benefits: ["Cleaner code", "Better maintainability", "Fewer bugs"];
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    drawbacks: ["More compiler errors", "Stricter refactoring requirements"];
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  };
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  /** Maximum strictness */
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  maximum: {
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    options: [
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      "strict",
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      "allowUnusedLabels: false",
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      "allowUnreachableCode: false",
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      "exactOptionalPropertyTypes",
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      "noFallthroughCasesInSwitch",
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      "noImplicitOverride",
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      "noImplicitReturns",
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      "noPropertyAccessFromIndexSignature",
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      "noUncheckedIndexedAccess",
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      "noUnusedLocals",
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      "noUnusedParameters",
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      "isolatedModules",
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      "checkJs"
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    ];
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    impact: "Maximum type safety and code quality";
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    benefits: ["Highest code quality", "Maximum type safety", "Comprehensive error detection"];
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    drawbacks: ["Steep learning curve", "Potential development overhead", "Legacy code challenges"];
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  };
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}
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```
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## Usage Patterns
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### Starting a New Project
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For new projects, begin with recommended configuration:
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```json
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{
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  "extends": "@tsconfig/recommended/tsconfig.json",
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  "compilerOptions": {
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    "outDir": "./dist",
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    "rootDir": "./src",
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    "declaration": true,
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    "sourceMap": true
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  },
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  "include": ["src/**/*"],
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  "exclude": ["node_modules", "dist", "**/*.test.ts"]
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}
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```
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### Production Applications
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For production code requiring maximum quality:
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```json
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{
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  "extends": "@tsconfig/strictest/tsconfig.json",
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  "compilerOptions": {
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    "outDir": "./build",
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    "rootDir": "./src",
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    "declaration": true,
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    "declarationMap": true,
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    "sourceMap": true
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  },
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  "include": ["src/**/*"],
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  "exclude": ["node_modules", "build", "**/*.spec.ts"]
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}
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```
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### Progressive Adoption
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Gradually increasing strictness over time:
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```json
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{
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  "extends": "@tsconfig/recommended/tsconfig.json",
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  "compilerOptions": {
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    "noImplicitReturns": true,
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    "noFallthroughCasesInSwitch": true,
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    "noUnusedLocals": true,
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    "noUnusedParameters": true
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  }
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}
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```
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### Combined Configurations
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Using multiple configurations together (TypeScript 5.0+):
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```json
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{
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  "extends": [
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    "@tsconfig/node20/tsconfig.json",
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    "@tsconfig/strictest/tsconfig.json"
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  ],
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  "compilerOptions": {
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    "outDir": "./dist"
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  }
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}
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```
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### Team Development
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Configuration for team development with consistent standards:
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```json
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{
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  "extends": "@tsconfig/strictest/tsconfig.json",
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  "compilerOptions": {
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    "baseUrl": ".",
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    "paths": {
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      "@/*": ["src/*"],
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      "@types/*": ["types/*"]
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    },
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    "plugins": [
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      {
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        "name": "typescript-plugin-styled-components"
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      }
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    ]
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  },
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  "include": ["src/**/*", "types/**/*"],
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  "exclude": ["node_modules", "dist", "**/*.test.ts", "**/*.spec.ts"]
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}
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```
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### Migration Strategy
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Migrating from JavaScript to TypeScript:
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```json
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{
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  "extends": "@tsconfig/recommended/tsconfig.json",
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  "compilerOptions": {
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    "allowJs": true,
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    "checkJs": false,
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    "noImplicitAny": false,
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    "strictNullChecks": false
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  },
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  "include": ["src/**/*"],
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  "exclude": ["node_modules"]
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}
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```
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Then gradually enable stricter options:
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```json
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{
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  "extends": "@tsconfig/recommended/tsconfig.json",
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  "compilerOptions": {
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    "allowJs": true,
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    "checkJs": true,
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    "noImplicitAny": true,
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    "strictNullChecks": true
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  }
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}
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```
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Finally, move to strictest:
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```json
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{
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  "extends": "@tsconfig/strictest/tsconfig.json",
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  "compilerOptions": {
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    "allowJs": false
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  }
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}
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```
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## Compiler Option Details
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Detailed explanation of key compiler options in general configurations:
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```typescript { .api }
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interface CompilerOptionDetails {
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  /** Core strictness options */
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  coreOptions: {
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    strict: "Enables all strict type checking options";
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    noImplicitAny: "Error on expressions with implied 'any' type";
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    strictNullChecks: "Enable strict null checks";
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    strictFunctionTypes: "Enable strict checking of function types";
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    strictBindCallApply: "Enable strict checking of bind/call/apply";
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    strictPropertyInitialization: "Enable strict checking of property initialization";
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    noImplicitReturns: "Error when not all code paths return a value";
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    noImplicitThis: "Error on 'this' expressions with implied 'any' type";
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  };
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  /** Quality enforcement options */
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  qualityOptions: {
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    noUnusedLocals: "Error on unused local variables";
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    noUnusedParameters: "Error on unused parameters";
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    noFallthroughCasesInSwitch: "Error on fallthrough cases in switch";
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    allowUnusedLabels: "Allow unused labels";
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    allowUnreachableCode: "Allow unreachable code";
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    exactOptionalPropertyTypes: "Differentiate between undefined and missing properties";
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    noPropertyAccessFromIndexSignature: "Require bracket notation for index signature access";
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    noUncheckedIndexedAccess: "Include undefined in index signature results";
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  };
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  /** Module system options */
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  moduleOptions: {
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    esModuleInterop: "Enable interoperability between CommonJS and ES modules";
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    allowSyntheticDefaultImports: "Allow default imports from modules with no default export";
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    forceConsistentCasingInFileNames: "Ensure consistent casing in file names";
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    skipLibCheck: "Skip type checking of declaration files";
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    isolatedModules: "Ensure each file can be safely transpiled in isolation";
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  };
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}
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```