tsconfig.json

{
  "files": ["src/index.ts"],
  "compilerOptions": {
    "target": "ESNext" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
    "lib": ["ESNext", "DOM", "DOM.Iterable"] /* Specify a set of bundled library declaration files that describe the target runtime environment. */,
    "module": "esnext" /* Specify what module code is generated. */,
    "rootDir": "src/" /* Specify the root folder within your source files. */,
    "moduleResolution": "Node",                     /* Specify how TypeScript looks up a file from a given module specifier. */
    "typeRoots": ["node_modules/@types"] /* Specify multiple folders that act like './node_modules/@types'. */,
    "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the 'checkJS' option to get errors from these files. */
    "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
    "declaration": true /* Generate .d.ts files from TypeScript and JavaScript files in your project. */,
    "declarationMap": true,
    "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
    "outDir": "lib/types" /* Specify an output folder for all emitted files. */,
    "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
    "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
    "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. */,
    "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied 'any' type. */
    "strictNullChecks": true /* When type checking, take into account 'null' and 'undefined'. */,
    "noUnusedLocals": true,                           /* Enable error reporting when local variables aren't read. */
    "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read. */
    "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
    "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
    "skipLibCheck": true /* Skip type checking all .d.ts files. */
  },
  "include": ["src/**/*.ts", "src/**/*.d.ts"],
  "exclude": ["src/test", "node_modules", "!node_modules/@types"]
}