tsconfig.json

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es6",
    "module": "commonjs",
    "lib": ["es6"],
    "declaration": true /* Generates corresponding '.d.ts' file. */,
    "declarationMap": true /* Generates a sourcemap for each corresponding '.d.ts' file. */,
    "sourceMap": true /* Generates corresponding '.map' file. */,
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    "outDir": "build" /* 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 Type-Checking Options */
    "strict": true /* Enable all strict type-checking options. */,
    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
  },
  "exclude": ["node_modules", "build"]
}