Generator生成器函数

// 生成器函数
function * foo () {
  console.log('start')
  try {
    const res = yield 'foo'
    console.log(res)
  } catch (e) {
    console.log(e)
  }
}
const generator = foo()
const result = generator.next()
console.log(result)

generator.throw(new Error('Generator error'))

管理异步流程
递归

function * main () {
  const users = yield ajax('/api/users.json')
  console.log(users)
  const posts = yield ajax('/api/posts.json')
  console.log(posts)
}

const g = main()
const result = g.next()
result.value.then(data => {
  const result2 = g.next(data)
  if (result2.done) return
  result2.value.then(data => {
    const result3 = g.next(data)
    if (result3.done) {
      result3.value.then(data => {
        const result4 = g.next(data)
      })
    }
  })
})

function * main () {
  try {
    const users = yield ajax('/api/users.json')
    console.log(users)
    const posts = yield ajax('/api/posts.json')
    console.log(posts)
  } catch(e) {
    console.log(e)
  }
}
const g = main()

function handleResult (result) {
  if (result.done) return
  result.value.then(data => {
    handleResult(g.next(data))
  }, error => {
    g.throw(error)
  })
}

handleResult(g.next())

function co (generator) {
const g = generator()
function handleResult (result) {
if (result.done) return
result.value.then(data => {
handleResult(g.next(data))
}, error => {
g.throw(error)
})
}
handleResult(g.next())
}
co(main)

执行器函数，线上成熟库地址 https://github.com/tj/co

Async/Await语法糖作用一致