That is a very childish thing to say. Windows has A LOT of problems. But it easy to use. Linux is still a tehnical operating system. And not everyone has the time or the know how to use it. And I use both. Plus, the majority of laptops and pcs come with windows, and installing Linux is not that simple. It will be at least 10 years before it becomes a somewhat widely used OS, with the younger generations being more used to tehnology in general.
That's from ESLint, not javascript itself. JS doesn't care about unused variables