思路

就是利用数组的filter方法进行过滤，不难

代码

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
	</head>
	<body>
		<select name="" id="">
			<option value="0">请选择销量范围</option>
			<option value="1">&lt100</option>
			<option value="2">100~500</option>
			<option value="3">&gt500</option>
		</select>
		<ul>
			<li>牛客logo马克杯</li>
			<li>无盖星空杯</li>
			<li>老式茶杯</li>
			<li>欧式印花杯</li>
		</ul>

		<script>
			var cups = [
				{ type: 1, price: 100, color: 'black', sales: 60, name: '牛客logo马克杯' },
				{ type: 2, price: 40, color: 'blue', sales: 100, name: '无盖星空杯' },
				{ type: 4, price: 60, color: 'green', sales: 200, name: '老式茶杯' },
				{ type: 3, price: 50, color: 'green', sales: 600, name: '欧式印花杯' },
			]
			var select = document.querySelector('select')
			var ul = document.querySelector('ul')
			// 补全代码
			let res = [] // 存放结果
			// 更新视图
			function updateDOM() {
				ul.innerHTML = ''
				let str = ''
				for (let i = 0; i < res.length; i++) {
					str += `<li>${res[i].name}</li>`
				}
				ul.innerHTML = str
			}
			select.onchange = function () {
				const value = this.options[this.options.selectedIndex].value
				if (value == 1) {
					res = cups.filter((item) => {
						return item.sales < 100
					})
          updateDOM()
				} else if (value == 2) {
					res = cups.filter((item) => {
						return item.sales >= 100 && item.sales <= 500
					})
          updateDOM()
				} else if (value == 3) {
					res = cups.filter((item) => {
						return item.sales > 500
					})
          updateDOM()
				}
			}
		</script>
	</body>
</html>