The extract.autodesk.io is well known as a tool to get the translated SVF dataset for Forge Viewer, and download them to local. My colleague Philippe Leefsma has written a cool blog on the simplified code extracting the SVF. The source code is tested with the comprehensive sample project forge-rcdb.nodejs. This sample is very helpful, but it is too comprehensive, and also using ES6, it is a bit challenge to some developers to isolate and just test with the process of extracting.
So, I took some time to make a very tiny test harness. you could simply input the client id and client secret of Forge, and the model urn. The code will extract the SVF and download it to client. The Github tells in details.
I am using Visual Code to develop. I'd recommend this blog that well introduces how to debug Node.js + ES6 in Visual Code:
Hope this helps.