There was the Netscape JS stuff, but I don't think it was nearly as popular as Classic ASP by 2000. I wrote a lot of ASP in JScript, was able to reuse validation libraries, etc for common inputs/forms which was nice at the time. I think the difficult points, were COM iterators were kind of alien feeling in JScript, and developing COM controls at the time were awkward and a real pain to debug/diagnose even in VS at the time.

Not to mention, very little in the space of Classic ASP was open-source, free or even anything not insanely expensive from what I recall at the time. What was in the box was pretty much just JS and VBS, and most of what you could piece together was sluggish as all hell. Cool, you can use the spell checker from MS-Word... damn, three users tried to use it at the same time on the server. etc.

I have some fond and nightmare memories from those days. I think in terms of before jQuery (though scriptaculous, prototype and others were cool), after jQuery and after Browserify and 6to5/Babel. The ESM transition is much, much slower going.