async/await - 8.在for循环中正确的使用await

async/await - 8.在for循环中正确的使用await

const fetch = require('node-fetch')
const bluebird  = require('bluebird')

async function getZhihuColumn(id) {
  await bluebird.delay(1000)
  const url = `https://zhuanlan.zhihu.com/api/columns/${id}`
  const response = await fetch(url)
  return await response.json()
}

循环中的串行

const showColumnInfo = async() => {
  console.time('showColumnInfo')

  const names = ['qianduanzhidian', 'FrontendMagazine']
  for (const name of names) {
    const column = await getZhihuColumn(name)
    console.log(`name:${column.name}`)
    console.log(`description:${column.description}`)
  }
  console.timeEnd('showColumnInfo') // 4757.181ms
}

showColumnInfo()

循环中的并行

const showColumnInfo = async() => {
  console.time('showColumnInfo')

  const names = ['qianduanzhidian', 'FrontendMagazine']
  const promises = names.map(x => getZhihuColumn(x))
  for (const promise of promises) {
    const column = await promise
    console.log(`name:${column.name}`)
    console.log(`description:${column.description}`)
  }
  console.timeEnd('showColumnInfo') // 2615.484ms
}

showColumnInfo()