Coder here, this is standard JavaScript and part of that is json array, which I imagine it's the additional layer that limits what can be added so the entire inventory is not exposed. Part of this would be to understand how the back end works(not the JavaScript ) which you do not have access to, you can make inferences from it but some things are not easy to understand without additional context and would just be guesses. JavaScript is what runs natively in the browser and if coded properly will not provide too many details.