js手写红绿灯（带优化版）

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>Document</title>
		<style>
			.container {
				display: flex;
			}
			.light {
				width: 100px;
				height: 100px;
				background-color: red;
			}
		</style>
	</head>
	<body>
		<div class="container">
			<div class="light"></div>
		</div>
		<script>
			let light = document.querySelectorAll('.light')
			let status = [
				{ color: 'red', delay: 2000 },
				{ color: 'yellow', delay: 1000 },
				{ color: 'green', delay: 3000 }
			]
			function getInterval() {
				let index = 1
				let diff
				return function interval(delay) {
					let startTime = +new Date().getTime()
					setTimeout(() => {
						let endTime = new Date().getTime()
						// 实际 - 理论 = 该减去的时间差
						diff = endTime - startTime - delay
						console.log('diff', diff)
						light[0].style.backgroundColor = status[index].color
						interval(status[index].delay - diff)
						index++
						index === 3 ? (index = 0) : ''
					}, delay)
				}
			}

			getInterval()(status[0].delay)
		</script>
	</body>
</html>

主要功能：红灯2秒后转黄灯，黄灯1秒后转绿灯

1.用时间补偿法纠正定时器

2.用闭包避免污染全局变量