JS Fetch API access return value [duplicate]

问题

This is how I access the result from a fetch call:

let data;

fetch(someUri)
    .then((response) => response.json())
    .then(_data => {
        data = _data;
    })
    .catch(error => {
        console.error(error);
    });

Is it also possible to access the result from the fetch function itself, like this:

let data = fetch(someUri)
    .then((response) => response.json())
    .then(data => {
        // do some stuff
        return data;
    })
    .catch(error => {
        return error;
    });

So data will be either the JSON data or the error. I see in my Chrome console that the result is in the variable, but I don't know how to access it because it's wrapped with other information.

回答1:

You can wrap it inside an immediately invoked async function and use await:

https://jsfiddle.net/ibowankenobi/ok72rfp6/

!async function(){
let data = await fetch("https://raw.githubusercontent.com/IbrahimTanyalcin/LEXICON/master/lexiconLogo.png")
    .then((response) => response.blob())
    .then(data => {
        return data;
    })
    .catch(error => {
        console.error(error);
    });

console.log(data);
}();

回答2:

Here are some good resources for fetch and an example.

https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API https://developer.mozilla.org/en-US/docs/Web/API/Body/text https://developer.mozilla.org/en-US/docs/Web/API/Body/json

You may also want to get familiar with promises. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

 
    function doSomethingWithText(text) {
        console.log('The text is:', text);
    }

    fetch('someUrl.html')
      .then(data => data.text())
      .then(text => (doSomethingWithText(text))
      .catch(error => new Error(error));

回答3:

fetch method returns a promise that resolves to a Response object.

Once you get the response, it is up to you what to do with it. You can use methods on response body like json, text or blob to get data into desired format to work with.

来源：https://stackoverflow.com/questions/50417982/js-fetch-api-access-return-value

标签

javascript

fetch