Test Task "Online market basket script". Probably the best thing I was able to do without almost no JavaScript knowledge is to follow this great course on udemy: "ES6 JavaScript Shopping Cart" - https://www.udemy.com/es6-javascript-shopping-cart/
2+ hours of detailed explanation of shopping cart creation, based on actual version of JS. This way not really meet the requirements of the task, but better than nothing.
Simply download the project and open index.html file in your browser.