tsconfig.json

{
  "files": ["src/index.ts"],
  "compilerOptions": {
    "target": "es5",
    "sourceMap": false,
    "declaration": true,
    "module": "es2015",
    "removeComments": false,
    "moduleResolution": "node",
    "experimentalDecorators": true,
    "strict": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "noImplicitAny": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitReturns": true,
    "noImplicitThis": true,
    "importHelpers": true,
    "stripInternal": true,
    "downlevelIteration": true,
    "lib": ["es6"],
    "useDefineForClassFields": true,
    "skipDefaultLibCheck": true,
    "skipLibCheck": true,
    "outDir": "lib"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "**/__tests__/*"]
}