javascript - 编辑 Promise 结果 (JavaScript)

Question

我想编辑一个 res.json，回调(Promise.then)的结果是像这样的关联数组 "{category:"tennis",data:res.json()}"

然后我想得到一个没有 Promise 类型的 it

我试过了，但它返回了 Promise 类型

const promise = new Promise(function(resolve,reject) {
  fetch("http://localhost:100/api/v1/categories/map").then(response
    => resolve(response.json()))
});





promise.then(value => Promise.all(value.category.map(
  category => {
     return (fetch("http://localhost:100/api/v1/categoriescategory=tennis"))
  }
))
.then(responses => {console.log(responses);
  return Promise.all(responses.map(res=> {
     console.log(res.json()) <- this is not Promise
  return(
  {category:"tennis",data:res.json()}  <- this is  Promise


)
} )
)}))
.then(value=>console.log(value)) // {{category:"tennis",Promise{data:data}} <- i want to unwrap Promise

Answer 1

因为 fetch 返回一个 Promise，并且使用 .json()(或 .text() 等)使用 Promise 给你另一个 Promise，你需要调用两次.then；将另一个 .then 放入您的初始映射函数中，就像您对初始 const promise 所做的那样。您还应该避免 explicit promise construction antipattern :

const promise = fetch("http://localhost:100/api/v1/categories/map").then(response => response.json());

promise.then(value => Promise.all(value.category.map(
  category => {
    return fetch("http://localhost:100/api/v1/categoriescategory=tennis")
      .then(response => response.json());
      // ^^^^^^^^^^^^^^^^^^^^^^^^^
  }
))
.then(responseObjects => {
  return Promise.all(responseObjects.map(responseObject => {
    return {
      category: "tennis",
      data: responseObject
    }
  }))
}))
  .then(value => console.log(value))