我怎样才能等到异步循环完成后才发送明确的回复？

Question

想做如下的事情。我认为这是异步调用的问题，因为我发送的响应始终是一个空数组，但 API 正在返回数据。非常新，非常感谢任何输入！

app.get('/:id/starships', (req, res) => {
  let person = findPersonById(people, req.params.id)[0];
  let starshipUrls = person.starships;
  for(let i=0; i<starshipUrls.length; i++){
    axios.get(starshipUrls[i]).then(response => {
      starships.push(response.data);
    })
    .catch(err => console.log(err));
  }
  res.json(starships);
})

Answer 1

axios.get returns一个promise. Use Promise.all等待多个promise:

app.get('/:id/starships', (req, res) => {
  let person = findPersonById(people, req.params.id)[0];
  Promise.all(person.starships.map(url => axios.get(url)))
    .then(responses => res.json(responses.map(r => r.data)))
    .catch(err => console.log(err));
})