tsconfig.json

{
  "compilerOptions": {
    "target": "ES2015",                          /* 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'. */
    "lib": ["ES6", "DOM"],                             /* Specify library files to be included in the compilation. */
    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    "outDir": "./dist",                        /* Redirect output structure to the directory. */
    "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    "strict": false,                           /* Enable all strict type-checking options. */
    "rootDirs": [
      "src"
    ],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
  },
  "exclude": [
    "src/__tests__/*",
  ]
}