异步

1

// 不输出5 // 不会输出6 因为then 返回的promise 没有resolve

new Promise((resolve, reject) => {
  console.log(1)
  resolve()
  setTimeout(() => {
    console.log(2)
  })

})
  .then(() => {
    console.log(3)
  })
  .then(() => {
    return new Promise((resolve, reject) => {
      console.log(4)
    }).then(() => {
      console.log(5)
    })
  })
  .then(() => {
    console.log(6)
  })
console.log(7)

2

//async1 start=> async2 start=>new promise=>async2 end=>new promise1=>new promise2=>async1 end=>new promise3

async function async1() {
  console.log('async1 start')
  await async2()
  console.log('async1 end')
}
async function async2() {
  console.log('async2 start')
  return Promise.resolve().then((res) => {
    console.log('async2 end')
  })
}
async1()
new Promise((resolve) => {
  console.log('promise')
  resolve()
})
  .then(function () {
    console.log('promise1')
  })
  .then(function () {
    console.log('promise2')
  })
  .then(function () {
    console.log('promise3')
  })

3

function* foo(x) {
  var y = 2 * (yield x + 1)
  var z = yield y / 3
  return x + y + z
}

var a = foo(5)
console.log(a.next()) 
console.log(a.next()) 
console.log(a.next())

var b = foo(5)
console.log(b.next()) 
console.log(b.next(12))
console.log(b.next(13))