tsconfig.json

{
  "compilerOptions": {
    "target": "es2017", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', or 'ESNEXT'. */
    "module": "commonjs", /* Specify module code generation: 'commonjs', 'amd', 'system', 'umd' or 'es2015'. */
    "lib": [ /* Specify library files to be included in the compilation:  */
      "es2017"
    ],
    "declaration": true, /* Generates corresponding '.d.ts' file. */
    "sourceMap": true, /* Generates corresponding '.map' file. */
    "strict": true, /* Enable all strict type-checking options. */
    "moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
    "emitDecoratorMetadata": true /* Enables experimental support for emitting type metadata for decorators. */
  }
}