如何访问异步获取函数的值? [英] How can I acces the values of my async fetch function?

问题描述

我想在另一个函数中使用获取的值

I want to use my fetched values in another function

我真的是JS新手.所以直到现在我都尝试了this.setState()和该函数的返回值.

I'm really new to JS. So until now I tried this.setState() and a return value of the function .

async fetchData() {

    const url = 'http://localhost:8080';
    const response = await fetch(url);
    const data = await response.json();
    // stringify JSON
    var myJSON = JSON.stringify(data);
    // parsing to JS object
    var jsonData = JSON.parse(myJSON);
 }

直到现在，我得到一个状态为"pending"的Promise.如何获得实际值?

until now, I'm getting a Promise with the status "pending" . How do I get the actual value?

推荐答案

将功能标记为

When you mark the function as async that implicitly wraps any return value it has with a Promise. You're not actually returning anything, so fetchData will just return a Promise that resolves to undefined.

因此，首先，您需要从函数中实际返回一些内容:

So first, you need to actually return something from your function:

async fetchData() {
  const url = 'http://localhost:8080';
  const response = await fetch(url);
  const data = await response.json();
  return data; // It should already be parsed JSON since you called `response.json()`
}

然后，您需要等待Promise在调用函数中完成:

Then you need to wait for the Promise to complete in the calling function:

// You can use async/await
async someOtherFunction() {
  const value = await fetchData();
  // Do things...
}

// Or use .then
someOtherFunction() {
  fetchData().then((value) => {
    // Do things...
  });
}

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