> Javascript was browser only until 2010

Depending on how you look at it you are at least a decade too late: we Java folks had the Rhino Javascript engine back in the late 1990ies, and it had an interpreted mode since 1998: https://en.wikipedia.org/wiki/Rhino_(JavaScript_engine)

I think it is even mentioned in the Javascript in a Nutshell book by David Flanagan (I haven't read it since then but I studied that book as I wrote a map rendering system in Javascript back in school in 2005.)

True, I played with Rhino, Jack / JSGI early on, and did a couple projects with Aptana Jaxer around 2009. It was not really an option most developers would even consider, though.

Node came out in 2009, and writing server-side JS was still a fringe practice for a couple more years, so 2010 is me being generous to avoid comments on the exact timeline ;) It really picked up mainstream adoption around 2011-2012.

Was Rhino ever anything other than a minefield that you were essentially pigeonholed into using for compatibility reasons or something similar? I have used it before but only because we had specific technical requirements that demanded we run Javascript on a server-side JVM implementation.

"Server-side JavaScript" was a feature of Netscape web servers in 1996.

At the end of the 90s Javascript was used to write a part of Dreamweaver and I mean the app itself, not the Javascript/HTML interface. So the language as always existed independently of browser implementations.