SOURCE

//promsie方法
function getData(data) {
  return new Promise((resolve, reject) => {
    if (data === 1) {
      setTimeout(() => {
        resolve('getdata success')
      }, 1000)
    } else {
      setTimeout(() => {
        reject('getdata error')
      }, 1000)
    }
  })
}

// window.onload = async () => {
//   let res = await getData(1)
//   console.log(res) //getdata success
// }

//1 扑获错误 try catch 方法
// try {
//     let res = await getData(3)
//     console.log(res)
//   } catch (error) {
//     console.log(res) //getdata error
// }
//2 then
// window.onload = async () => {
//   let res = await getData(3).then(r=>r).catch(err=>err);
//   console.log(res) //getdata error
// }

//3 better 
window.onload = async () => {
  let res = await getData(1)
  .then((res) => [null, res])
  .catch((err) => [err, null])
  console.log(res) // ["getdata error",null]
}

//4 封装成工具函数
function awaitWrapper(pro){
    return pro
    .then((res)=>[null,res])
    .catch((err)=>[err,null])
}
window.onload = async ()=>{
    let res = await awaitWrapper(getData(3))
    console.log(res)
}