async 捕捉错误

• try…catch

• 返回的数据正确的和错误合并到一起处理

  const fn = async() => {
  	let res&&err = await fetchFn().then(res => res).catch(err => err)
  }
  

• 返回的数据正确的和错误的分开处理

  const fn = async() =>{
  	let [err,res] = await fetchFn().then(res =>[null,res].catch(err => [err,null]))
  }