模拟红绿灯

红灯3s，绿灯2s，黄灯1s，如此循环

async await 实现

async function task (list) {
  for (let i = 0; i < list.length; i++) {
    await light(...list[i])
  }
  await task(list)
}

async function light(s, time) {
  console.log(`${s} 开始了`)
  await new Promise(resolve => {
    setTimeout(resolve, time)
  })
  console.log(`${s} 结束了`)
}

const list = [
  ['红灯', 3000],
  ['绿灯', 2000],
  ['黄灯', 1000]
]
task(list)