function muti (num) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve(num * num)  
    }, 1000)
  })
}

const nums = [1, 2, 3]

// 同步遍历
// nums.forEach(async (i) => {
//   const res = await muti(i)
//   console.log(res)
// })


// 异步遍历
!(async function () {
  for (i of nums) {
    const res = await muti(i)
    console.log('for...of', res)
  }
})()

!(async function () {
  for (let i = 0; i < nums.length; i++) {
    const res = await muti(nums[i])
    console.log('for', res)
  }
})()

!(async function () {
  for (i in nums) {
    if (nums.hasOwnProperty(i)) {
      const res = await muti(nums[i])
      console.log('for...in', res)
    }
  }
})()