tsconfig.json

{
  "compilerOptions": {
    "moduleResolution": "node",
    "module": "commonjs",
    "baseUrl": "src",
    "removeComments": true,
    "importHelpers": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "suppressImplicitAnyIndexErrors": true,
    "noUnusedLocals": true,
    "resolveJsonModule": true,
    "downlevelIteration": true,
    "lib": ["esnext", "es6"],
    "strict": true,
    "declaration": true,
    "allowSyntheticDefaultImports": true,
    "declarationDir": "typings",
    "outDir": "lib",
    "types": ["jest", "node"],
    "typeRoots": [
      "node_modules/@types"
    ],
    "esModuleInterop": true,
    "allowJs": true,
    "target": "ES2019",
    "strictFunctionTypes": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src/**/*.ts", "__tests__/**/*.ts"],
  "exclude": ["node_modules"]
}