tsconfig.json

{
  "compilerOptions": {
    "target": "es6",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "outDir": "./lib",                        /* Redirect output structure to the directory. */
    "rootDir": "./src",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    "strict": true,                           /* Enable all strict type-checking options. */
    "noImplicitAny": true,                    /* Raise error on expressions and declarations with an implied 'any' type. */
    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
    "sourceMap": true,
    "noImplicitOverride": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitReturns": true,
    "noPropertyAccessFromIndexSignature": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "experimentalDecorators": true
  },
  "exclude": ["node_modules", "**/*.spec.ts"]
}