Uses of javascript, not just for aesthetics but uses on the server side

Uses of javascript, not just for aesthetics but uses on the server side References I have read this article (Uses of Javascript), while it is right I know there are other uses of javascript, modern javascript nowadays. I haven\'t read about node.js and how this one works but I have heard that this one makes js do server-side stuffs? The question is, what are other uses of javascript, can this replace php and ruby? I know this might not be a good idea for enterprise applications but will work well with medium-size applications, am I right? What are the other uses of javascript other than the one given in the article?