I think knowing about frontend is important for a senior or higher level engineer. I would expect someone at that level to be able to contribute where necessary, and know enough to make sane decisions and know when those decisions impact backend/frontend. But to be equally good at both isn't reasonable
Oh are you talking about creating the object? Yeah I think you might get better answers in a TS thread, because that question and the response here makes no sense in most statically typed languages.
I don't have custom wallpapers on my computers for some reason.