upbtn.onclick = function () { let newCups = cups.sort(function (a, b) { return a.sales - b.sales }) newCups.map((obj) => { let li = document.createElement('li') li.innerHTML = obj.name ul.append(li) }) } downbtn.onclick = function () { let newCups = cups.sort(function (a, b) { return b.sales - a.sales }) newCups.map((obj) => { let li = document.createElement('li') li.innerHTML = obj.name ul.append(li) }) }