You don't have to import folder as you mentioned. It's actually done by webpack resolve https://webpack.js.org/configuration/resolve/#resolve-extensions
By default webpack is looking for .js and .json extensions that means when you import import Foo from './Foo' it will try to look ./Foo/index.js or ./Foo/index.json if it is found, it is automatically imported. If you need to extend this to typescript you need to specify
resolve: {
extensions: ['.js', '.json', '.ts']
}
of course in this way you have to specify ts-loader to handle typescript files https://github.com/TypeStrong/ts-loader which will take care of transpilation from typescript when it is imported.