tsconfig.json

{
  "compilerOptions": {
    "resolveJsonModule": true,
    /* Basic Options */
    "target": "ES3",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
    "module": "es2015",                       /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "declaration": true,                      /* Generates corresponding '.d.ts' file. */
    "rootDir": "./src",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    /* Strict Type-Checking Options */
    "strict": true,                           /* Enable all strict type-checking options. */
    /* Module Resolution Options */
    "moduleResolution": "node",               /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
    /* Advanced Options */
    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
  },
  "exclude": [
    "**/*.spec.ts",
    "node_modules",
    "specs"
  ]
}