tsconfig.json

{
  "compilerOptions": {
    "lib": [
      "es5",
      "es6",
      "es2019"
    ],
    "target": "es5",
    "outDir": "./dist",
    "esModuleInterop": true,
    "declaration": true,
    "module": "commonjs",
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "sourceMap": true,
    "noImplicitReturns": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "noImplicitThis": true,
    "allowJs": true,
    "skipLibCheck": true,
    "downlevelIteration": true // to use ES5 specific tooling
  },
  "include": ["src"],
  "exclude": [
    "dist",
    "src/**/__tests__",
    "src/**/__mocks__",
    "src/**/__fixtures__",
    "node_modules"
  ]
}