My company has multiple applications written in jQuery and Bootstrap that are now 10+ years old and going strong. We've been using Node.js on the backend for a little over 3 years now and those apps aren't going anywhere for quite some time. I think the notion of the continually shifting Javascript landscape has been overplayed. To wit, C++ has been changing more frequently than Javascript has!
You can possibly work with and update a C# program because of the incredible longevity/backward compatibility of the core libraries, and reasonable commitment to this in the culture of the ecosystem.
But in Javascript land this can easily or even typically hit a point where the errors from package churn are so much that economically the juice is not worth the squeeze, in a literal order of magnitude less than the typical C# system.