tsconfig.json

{
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig to read more about this file */

    /* Language and Environment */
    "target": "ES2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,

    /* Modules */
    "module": "CommonJS" /* Specify what module code is generated. */,

    /* Emit */
    "declaration": true /* Generate .d.ts files from TypeScript and JavaScript files in your project. */,
    "outDir": "./lib",
    /* Interop Constraints */
   "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables 'allowSyntheticDefaultImports' for type compatibility. */,
   "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,

    /* Type Checking */
    "strict": false /* Enable all strict type-checking options. */,
    "strictNullChecks": true /* When type checking, take into account 'null' and 'undefined'. */,

    /* Completeness */
    "skipLibCheck": true /* Skip type checking all .d.ts files. */
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "**/tests/**/*", "src/**/*.test.ts"]
}