I use the Node.js client on occasion for inspection or testing, but, knowing the advantages of using stored procedures, I have adopted a pattern of doing all database operations for production code inside of stored procedures.
However, the infrastructure around DocumentDB is not yet mature. A particularly painful aspect of this is that it's missing a good way to test and debug your stored procedures. Sure, you can attach execution state to the "body" that is returned from the run to see what's going on, but it would be much easier if you could use your local debugger and write automated tests to confirm the functionality before you pushed your stored procedure to the server.
So, you can find it on npm at https://www.npmjs.com/package/documentdb-mock or GitHub at https://github.com/lmaccherone/documentdb-mock.
As always I appreciate input and pull requests.
Analysis and Visualization running on Node.js, DocumentDB, and Earl Grey Tea