SOURCE

// 参考:https://juejin.cn/post/7082286353957781517?searchId=202308181023404165555042A2AB793714
// 用js模拟写一个交通信号灯，红灯亮5秒后变成绿灯  绿灯亮2秒后变成黄灯  黄灯亮5秒后变成红灯
let light = [
    {color:'red', duration: 5000},
    {color:'green', duration: 2000},
    {color:'yellow', duration: 5000},
]
let index = 0
function changeLight(color, during){
    console.log(`${color}灯亮${during/1000}秒`)
    // 切换灯 等待during s 后切换, 如何让调用方感知呢?
    return new Promise((resolve, reject)=>{
        setTimeout(()=>{
            resolve()
        },during)
    })


}

// 启动红绿灯
async function start(){

    await changeLight(light[index].color, light[index].duration)
    index++
    index = index%3
    //阻塞下文
    start()

}

start()