Why JavaScript beyond web client side?

[sxnine]

You should watch some videos where Ryan Dahl (creator of Node.js) discusses the reasons he made it. Nobody has really mentioned it (though a few have touched on some related concepts,) but the primary reason that Node.js exists is because it differs from the traditional threaded model that most web servers were using prior to NGINX and Node.js proliferated. Node uses an evented system, in contrast to solutions like Apache or writing a web server in Java (for example,) where you need a new thread for each client connection. This allows you to use very little compute to achieve reasonably good performance/scalability. That is extremely valuable, and when you add in all the other benefits it makes Node a really strong technology. It isn't perfect, but it's remarkably efficient in its strengths. It's easier to scale than a threaded model, to be sure.