select.onchange = function() { ul.innerHTML = ''; switch(this.value) { case '1': var newArr = cups.filter((item) => { return item.sales<100 }) break; case '2': var newArr = cups.filter((item) => { return item.sales<=500 && item.sales>=100 }) break; case '3': var newArr = cups.filter((item) => { return item.sales>500 }) break; } initList(newArr) } function initList(arr) { arr.forEach(item => { let Li = document.createElement('li'); Li.innerHTML = item.name; ul.appendChild(Li); }) }