tsconfig.json

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "declaration": true,
    "experimentalDecorators": true,
    "lib": [
      "dom",
      "es2017"
    ],
    "module": "esnext",
    "moduleResolution": "node",
    "noImplicitAny": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "outDir": "dist/esm",
    "sourceMap": true,
    "target": "es2017"
  },
  "files": [
    "src/index.ts"
  ]
}