tsconfig.json

{
  "include": ["src/**/*.js", "tests/**/*.js"],
  "compilerOptions": {
    // Tells TypeScript to read JS files, as
    // normally they are ignored as source files
    "allowJs": true,
    // flag any errors found in .js files
    "checkJs": true,
    // Generate d.ts files
    "declaration": true,
    // This compiler run should
    // only output d.ts files
    "emitDeclarationOnly": false,
    // go to js file when using IDE functions like
    // "Go to Definition" in VSCode
    "declarationMap": true,
    // The type definition files go here:
    "outDir": "dist",
    // The output will be in ES6, not the default ES3
    "target": "es6",
    // modules in src are the old fashioned "node" type modules
    "moduleResolution":"node",
  }
}