tsconfig.json

{
    "include": [
      "index.ts",
    ],
    "exclude": [
        "test"
    ],
    "compilerOptions": {
      "target": "ES2016",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
      "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
      "allowJs": false,                         /* Allow javascript files to be compiled. */
      "outDir": "./",                           /* Redirect output structure to the directory. */
      "declaration": true,
      
      /* Module Resolution Options */
      "moduleResolution": "node",               /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
      "baseUrl": "./",                          /* Base directory to resolve non-absolute module names. */
      "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
  
      /* Source Map Options */
      "sourceMap": true
    }
  }