for await of異步操作集合遍歷

function Gen (time) {
  return new Promise((resolve,reject) => {
    setTimeout(function () {
       resolve(time)
    },time)
  })
}

async  function test () {
   let arr = [Gen(2000),Gen(100),Gen(3000)]
   for await (let item of arr) {
      console.log(Date.now(),item)
   }
}
test()