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);
  })
}