Wait, you’re in the final months of a CS degree and you haven’t learnt any programming languages??
You have a short period of time, you need something you can build in quickly and has lots and lots of tutorials for beginners. Ruby (using Ruby on Rails), Python (using Flask or Django), JS (using Express) fulfil this. So does PHP, but I’ve not used it for a very long time so can’t advise. JS tends be the least friendly language-wise but is available everywhere and probably has the most resources (though many go out of date quickly). If you have a few months, you don’t have time to learn a language properly.
Also: this idea is not focussed in any way (and not a particularly interesting thing w/r/t CS). Some aspect of it - like a novel payment system for e-commerce or whatever - that’s feasible and you might be able to actually finish it and make use use of the knowledge gained from the degree. What you’re suggesting is a big engineering problem, not a CS problem. Can you do it in JS? Sure. But an e-commerce site is just a tiny piece of UI, there isn’t anything special about a site (this is why what you are doing as degree matters: eg if you were doing a design degree, then the UI would matter, the backend would be irrelevant). What it actually is is the interface for a collection of lots of other things; that’s why I say it’s not focussed, because just saying you want to make an e-commerce site - that’s not really a thing in isolation, per se