ES6 generator 用法问题

Question

var api1 = 'https://anapioficeandfire.com/api/characters/583'var api2 = 'https://anapioficeandfire.com/api/characters/584'function *fetchData () {  var res = yield request(api1)  res.json().then(data => {    console.log(data.name) // Jon Snow  })}function request (url) {  fetch(url).then(res => {    it.next(res)  })}var it = fetchData()it.next()var api1 = 'https://anapioficeandfire.com/api/characters/583'var api2 = 'https://anapioficeandfire.com/api/characters/584'function *fetchData () {  var res = yield fetch(api1).then(data => fetchData().next(data))  res.json().then(data => {    console.log(data.name)  })}fetchData().next()第一段代码可以正确打印出结果，而第二段代码却不行，想问下为什么，我觉得两段代码并没有区别

Answer 1

第一段代码，两个对方都是对it做的next.

第二段代码，两个地方是分别对两个不同的generator做的next

当然结果不同