问: 如何通过promise、async+await, 实现红绿灯的切换,并在控制台打印输出, 红灯亮30s, 黄灯亮5s, 绿灯亮20s
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Promise</title>
</head>
<body>
<script>
// 通过面向对象编程来实现
class LightController {
constructor() {
this