tsconfig.json

{
  "compilerOptions": {
    "baseUrl": ".",
    "module": "ESNext",
    "moduleResolution": "node",
    "sourceMap": true,
    "strict": true,
    "noImplicitReturns": true,
    "noImplicitAny": true,
    "target": "ES6",
    "lib": [
      "ESNext",
      "DOM",
      "DOM.Iterable"
    ]
  },
  "files": [
    "src/index.ts"
  ]
}