When I am importing one js file into another js, normally I am using following syntax.

```
var userControllerObj = require("../controller/userController"),
        userController = new userControllerObj.UserGatewayController();

```

> 
> My doubt is, can I use let or const instead of var. I know that, these
>  3 data types have different scope. Still am having confusing between
>  const and let.Some one please explain it.
> 
> 
>