Javascript Fetch API - How to save output to variable as an Object (not the Promise)

问题

Please, how can I save output of fetch to a variable - to be able to work with it as with an object?

Here is the code:

var obj;
fetch("url", {
  method: "POST",
  body: JSON.stringify({
    "filterParameters": {
      "id": 12345678
    }
  }),
  headers: {"content-type": "application/json"},
  //credentials: 'include'
})
.then(res => res.json())
.then(console.log)

The final console.log will show an object. But when I tried to save it to variable .then(res => obj = res.json()) than the console.log(obj) will not hold the Object, but the Promise.

Any idea please, how to turn it into an Object saved in the variable?

回答1:

.json() is an async method (it returns a Promise itself), so you have to assign the parsed value in the next .then()

var obj;

fetch('https://jsonplaceholder.typicode.com/posts/1')
  .then(res => res.json())
  .then(data => obj = data)
  .then(() => console.log(obj))

来源：https://stackoverflow.com/questions/45018338/javascript-fetch-api-how-to-save-output-to-variable-as-an-object-not-the-prom