tsconfig.build.json

{
  "compilerOptions": {
    "baseUrl": "./src",
    // Enables all strict type checking options.
    "strict": true,
    // enables "core language features"
    "lib": [
      // ESNext auto includes previous versions all the way back to es5
      "esnext"
    ],
    // Node 8 should support everything output by esnext, we override this
    // in webpack with loader-level compiler options
    "target": "ES2015",
    // Use commonjs for node, overridden in webpack to keep import statements
    // to maintain support for things like `await import()`
    "module": "commonjs",
    // Allows default imports from modules with no default export. This does not affect code emit, just type checking.
    // We have to enable this option explicitly since `esModuleInterop` doesn't enable it automatically when ES2015 or
    // ESNext module format is used.
    "allowSyntheticDefaultImports": true,
    // Emits __importStar and __importDefault helpers for runtime babel ecosystem compatibility.
    "esModuleInterop": true,
    // Resolve modules in the same way as Node.js. Aka make `require` works the
    // same in TypeScript as it does in Node.js.
    "moduleResolution": "node",
    // Disallow inconsistently-cased references to the same file.
    "forceConsistentCasingInFileNames": true,
    // Forbid unused local variables as the rule was deprecated by ts-lint
    "noUnusedLocals": true,
    // Provide full support for iterables in for..of, spread and destructuring when targeting ES5 or ES3.
    "downlevelIteration": true,
    // import tslib helpers rather than inlining helpers for iteration or spreading, for instance
    "importHelpers": true,
    // adding global typings
    "types": ["jest", "node"],
    "declaration": true,
    "outDir": "lib"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules/**/*", "src/**/*.test.ts"]
}