JS runtime in Rails

When we develop rails apps, we usually need JavaScript runtime. On Mac OS X and Windows a JavaScript runtime is already installed in the operating system. For Linux, we usually install node.js, because it uses the Google V8 JavaScript engine, which is super fast.

It’s worth noting, that processing JavaScript (without executing it) would not principally require a JavaScript runtime. The reason why the Rails asset pipeline needs a JavaScript runtime is that it does the processing with tools like CoffeeScript and uglifier that themselves are implemented in JavaScript and which thus require a runtime to be used.