A quick study focused on Mongo-Node, using socket.io for carriage
Mongo still mystifies me and I need to get better at it.
This shows how to send some data (which here is hard-coded, but could easily come from a click handler in your app) from the client back to the server using socket.io.
Once it gets there, the server logic in app.js shows both how to save that data in a local disk file, as well as how to store it using MongoDB.