Function fixConfig

packages/node/src/typescript.ts:470–516

(
  config: { compilerOptions: any },
  nodeVersionMajor = 12
)

 * Do post-processing on config options to support `ts-node`.
 */
export function fixConfig(
  config: { compilerOptions: any },
  nodeVersionMajor = 12
) {
  if (!config.compilerOptions) {
    config.compilerOptions = {};
  }
  // Delete options that *should not* be passed through.
  delete config.compilerOptions.out;
  delete config.compilerOptions.outFile;
  delete config.compilerOptions.composite;
  delete config.compilerOptions.declarationDir;
  delete config.compilerOptions.declarationMap;
  delete config.compilerOptions.emitDeclarationOnly;
  delete config.compilerOptions.tsBuildInfoFile;
  delete config.compilerOptions.incremental;

  // This will prevent TS from polyfill/downlevel emit.
  if (config.compilerOptions.target === undefined) {
    // See https://github.com/tsconfig/bases/tree/main/bases
    let target: string;
    if (nodeVersionMajor >= 16) {
      target = 'ES2021';
    } else if (nodeVersionMajor >= 14) {
      target = 'ES2020';
    } else {
      target = 'ES2019';
    }
    config.compilerOptions.target = target;
  }

  // When mixing TS with JS, its best to enable this flag.
  // This is useful when no `tsconfig.json` is supplied.
  if (config.compilerOptions.esModuleInterop === undefined) {
    config.compilerOptions.esModuleInterop = true;
  }

  // nodenext will defer to the package.json#type field
  // but still respect .mts and .cts files
  if (config.compilerOptions.module === undefined) {
    config.compilerOptions.module = 'NodeNext';
    config.compilerOptions.moduleResolution = 'NodeNext';
    config.compilerOptions.strict = false;
  }

  return config;
}

/**
 * Internal source output.