This document will help you get started with controlling an Orbotix Sphero using Node.js.
There are several different libraries for controlling the Sphero. Currently, the best one seems to be spheron. This module provides a simple interface to the Sphero API.
There is also CylonJS, but this just uses the spheron module and exposes the same API, so unless you are already using Cylon to control different hardware it probably makes sense to just use spheron directly.