tsconfig-swc

Translate a tsconfig JSON object into a swcrc JSON object with comprehensive mapping support.

• Comprehensive mapping: Supports most TypeScript compiler options
• JSX support: Full React JSX transformation configuration
• Decorators: Experimental decorators and metadata support
• Path mapping: baseUrl and paths configuration
• Source maps: Complete source map configuration
• Module systems: CommonJS, ES6, AMD, UMD support
• Type-safe: Full TypeScript type definitions

Installation

npm install tsconfig-swc

Usage

import convert from "tsconfig-swc";

const tsconfig = {
  compilerOptions: {
    target: "ES2020",
    module: "CommonJS",
    jsx: "ReactJSX",
    experimentalDecorators: true,
    sourceMap: true,
  },
};

const swcConfig = convert(tsconfig);
console.log(swcConfig); // SWC configuration object

Configuration Mapping

This table shows how TypeScript compiler options map to SWC configuration options:

Core Compilation Options

| TSConfig Option | SWC Equivalent | Notes | | --------------- | ------------------- | ---------------------------------------------------------- | | target | jsc.target | Maps ES versions (ES5 → es5, ES2020 → es2020, etc.) | | module | module.type | Maps module systems (CommonJS → commonjs, ES6 → es6, etc.) | | lib | N/A | Handle via environment/polyfills, not SWC | | allowJs | jsc.parser.syntax | Influences syntax detection | | checkJs | N/A | TypeScript-only feature |

JSX Configuration

| TSConfig Option | SWC Equivalent | Notes | | -------------------- | ----------------------------------------------- | ------------------------------------------------------ | | jsx | jsc.parser.jsx, jsc.transform.react.runtime | Maps JSX modes (React → classic, ReactJSX → automatic) | | jsxFactory | jsc.transform.react.pragma | React pragma function | | jsxFragmentFactory | jsc.transform.react.pragmaFrag | React fragment pragma | | jsxImportSource | jsc.transform.react.importSource | Import source for automatic runtime |

Decorators & Experimental Features

| TSConfig Option | SWC Equivalent | Notes | | ------------------------- | -------------------------------------------------------- | ----------------------------------- | | experimentalDecorators | jsc.parser.decorators, jsc.transform.legacyDecorator | Enables decorator support | | emitDecoratorMetadata | jsc.transform.decoratorMetadata | Decorator metadata emission | | useDefineForClassFields | jsc.transform.useDefineForClassFields | Class field initialization behavior |

Module Resolution & Paths

| TSConfig Option | SWC Equivalent | Notes | | ------------------ | -------------- | ------------------------------ | | baseUrl | jsc.baseUrl | Base URL for path resolution | | paths | jsc.paths | Path mapping configuration | | moduleResolution | N/A | Handled by bundler/environment | | typeRoots | N/A | TypeScript-only feature | | types | N/A | TypeScript-only feature |

Module Interop & Imports

| TSConfig Option | SWC Equivalent | Notes | | ------------------------------ | ------------------ | ----------------------------------------------------------- | | esModuleInterop | module.noInterop | Inverted mapping (esModuleInterop: false → noInterop: true) | | allowSyntheticDefaultImports | N/A | Handled by module system | | resolveJsonModule | N/A | Handled by bundler | | preserveSymlinks | N/A | Handled by module resolver |

Source Maps & Output

| TSConfig Option | SWC Equivalent | Notes | | ----------------- | ------------------------- | -------------------------------------------------------------------- | | sourceMap | sourceMaps: true | External source maps | | inlineSourceMap | sourceMaps: 'inline' | Inline source maps | | inlineSources | inlineSourcesContent | Include source content in maps | | removeComments | jsc.preserveAllComments | Inverted mapping (removeComments: false → preserveAllComments: true) |

Helpers & Optimization

| TSConfig Option | SWC Equivalent | Notes | | -------------------- | ------------------------------------ | ----------------------------------- | | importHelpers | jsc.externalHelpers | Use external helper functions | | downlevelIteration | N/A | SWC handles iteration automatically | | preserveConstEnums | jsc.transform.treatConstEnumAsEnum | Const enum behavior |

TypeScript-Only Options

These options are TypeScript compiler-specific and have no SWC equivalent:

| TSConfig Option | Notes | | ---------------------------------- | --------------------------------------------------- | | declaration | Type declaration generation (use tsc for this) | | declarationMap | Declaration source maps (use tsc for this) | | emitDeclarationOnly | Declaration-only compilation (use tsc for this) | | outDir | Output directory (handled by build tools) | | outFile | Single file output (use bundler) | | rootDir | Root directory (handled by build tools) | | noEmit | No emit mode (use tsc --noEmit for type checking) | | strict | Type checking option, not compilation | | noImplicitAny | Type checking option, not compilation | | strictNullChecks | Type checking option, not compilation | | strictFunctionTypes | Type checking option, not compilation | | noImplicitReturns | Type checking option, not compilation | | noFallthroughCasesInSwitch | Type checking option, not compilation | | skipLibCheck | TypeScript-only optimization | | forceConsistentCasingInFileNames | TypeScript-only file system check |

Examples

Node.js Project

// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2020",
    "module": "CommonJS",
    "strict": true,
    "esModuleInterop": true,
    "sourceMap": true,
    "outDir": "dist"
  }
}

// Generated .swcrc
{
  "$schema": "https://swc.rs/schema.json",
  "jsc": {
    "parser": { "syntax": "typescript" },
    "target": "es2020"
  },
  "module": {
    "type": "commonjs",
    "strict": true
  },
  "sourceMaps": true
}

React Application

// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2020",
    "module": "ESNext",
    "jsx": "ReactJSX",
    "jsxImportSource": "@emotion/react",
    "strict": true,
    "moduleResolution": "node"
  }
}

// Generated .swcrc
{
  "$schema": "https://swc.rs/schema.json",
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "jsx": true,
      "tsx": true
    },
    "target": "es2020",
    "transform": {
      "react": {
        "runtime": "automatic",
        "importSource": "@emotion/react"
      }
    }
  },
  "module": {
    "type": "es6"
  }
}

Library with Decorators

// tsconfig.json
{
  "compilerOptions": {
    "target": "ES2017",
    "module": "UMD",
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "useDefineForClassFields": false,
    "declaration": true
  }
}

// Generated .swcrc
{
  "$schema": "https://swc.rs/schema.json",
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "decorators": true
    },
    "target": "es2017",
    "transform": {
      "legacyDecorator": true,
      "decoratorMetadata": true,
      "useDefineForClassFields": false
    }
  },
  "module": {
    "type": "umd"
  }
}