How to find all the variants that I need in a page source page?

I have been viewing the HTML source a product page on a website to find out exactly how many items are in stock for each variant for a particular product.

I have managed to find out how many are in stock within the company as a whole, by accessing there production page. But i want to be able to see how many there are of each size (the site is Adidas). Plus it would be great to be able to find out the exact drop times for the items as they are meant to be 'random' but i know from the product page (and others who have managed to crack it) that all this can be done using JSON.

If anyone could help that would be fantastic i have spent almost 72 hours on this so it is safe to say i am a complete novice here.

This is what I have come up with so far here .