tsconfig.json

{
  "compileOnSave": true,
  "compilerOptions": {
    "target": "es6",
    "module": "es6",
    "declaration": true,
    "outDir": "./lib",
    "strict": true,
    "lib": ["es6", "es2017.object", "DOM"],
    "allowSyntheticDefaultImports": true
  },
  "exclude": ["node_modules"]
}