Get User Selection value for woocommerce webapp.

I have a woocommerce website. I am scrapping products from different websites and displaying them on my website. Whenever user selects any specific product, I run my scrapper, and get the latest stock (quantity) and price of that particular product from another website. Now, I want that for the products with variations like color and size, whenever user selects any specific color and size, I get the selected values to pass them to my scrapper (scrapper is in [login to view URL] file) . You will need to find out, how I get to know what color and size user has selected from single product page, so I can pass the selected values to scrapper. One more thing, I need to get the selected values right after the user selects them from dropdowns as I need to show the stock and price on selection of these 2 parameters (color and size).