JS编写一个TrafficLightController类

/**
编写一个TrafficLightController类，实现红绿灯状态切换，并在控制台打印输出
(1)start()方法，实现红绿灯切换，绿灯30s/黄灯3s/红灯20s
(2)changeDuration()方法，可以实现改变红绿灯持续时间
(3)stop方法，停止切换
可以使用promise/async/await
*/
class TrafficLightController {
    constructor() {
        this.greenDuration = 30
        this.redDuration = 20
        this.yellowDuration = 3
    }
    async start() {
        console.log("绿灯亮",Date.now())
        await this.delay(this.greenDuration)
        console.log("红灯亮",Date.now())
        await this.delay(this.redDuration)
        console.log("黄灯亮",Date.now())
        await this.delay(this.yellowDuration)
    }
    async delay(duration){
        return new Promise(resolve=>{
            setTimeout(resolve,duration*1000)
        })
    }
    changeDuration(type, duration) {
        switch (type){
            case "green":
                this.greenDuration = duration
                break
            case "red":
                this.redDuration = duration
                break
            case "yellow":
                this.yellowDuration = duration
                break
            default:
                throw new Error("无效type")
        }
    }
    stop() {
        this.isStop = true
    }
}
let traffic = new TrafficLightController()
traffic.changeDuration("red",7000)
traffic.start()