Speaking of Node.js, there are a number of tools for the ArcGIS JavaScript API that rely on Node.js. The ArcGIS API for JavaScript Web Optimizer is a Node.js project hosted by ESRI, which packages your custom modules along with a minimum set of ESRI and Dojo modules for a simplified build process. You can host through ESRI's content delivery network (CDN), or download and host it yourself.

If you decide to focus more on the Web AppBuilder Developer Edition, there's a Node.js project for that, too. The generator-esri-appbuilder-js project generates a template Web AppBuilder widget with all the necessary files. It asks you for basic information, such as the widget name and author information, as well as what kinds of files the widget will require. The project is based on Yeoman, a Node.js template-generating tool.