You could convert some simple work files and showcase the benefit on how it’ll be better than JS. Show them how the “extra fluff” will benefit them in a context witch everyone is familiar with.
The problem is, it's not always possible (if managers refuse to let you do it in the first place) or practical (if you don't get given the time or if you're working with a complicated legacy setup and can't make those kind of changes).
The problem is people can only really see the benefit by working with it for a while, but to work with it there needs to be some initial work to introduce it.