Finally have a graph displaying some Trademe data. There as a steep learning curve on the Node.js side. I ended up with a web server built on express, using pug (formerly Jade) templates for HTML formatting and returning JSON data from asynchronous client side calls. This may not be the best way but have something up and running which I can add to.
For learning Node.js and Express I did an excellent tutorial (although it used MongoDB) and lots of small scripts to learn about callbacks, avoiding callback hell and asynchronous flow control using async.
The graphing library I am going to use is D3 on the client side. It may be – them on the server is best but for now just using the library in various ways will be fine from client side.
Anyway, from the Trademe development sandbox a graph of number of listings per locality. That’s the minimum product up and running.