即使在使用'then'后，Fetch也会返回promise而不是实际数据 [英] Fetch returns promise instead of actual data even after using 'then'

问题描述

我正在我的组件中进行一个简单的fetch调用，看起来像这样

I am making a simple fetch call in my component, which looks like this

    var x = fetch(SOME_URL, SOME_POST_DATA)
             .then((response) => response.json())
             .then((responseJSON) => {return responseJSON});

    console.log(x);

调用成功执行但控制台打印的是promise而不是数据。我在这里缺少什么？

The call executes successfully but the console prints a promise instead of data. What am I missing here?

推荐答案

Promises的工作方式意味着你需要处理 responseJSON 里面 的处理程序然后是（）。由于请求的异步性，外部代码已经在promise解析时返回。

The way promises works mean you'll need to handle the responseJSON inside the handler for then(). Due to the asynchronous nature of requests the outer code will already have returned by the time the promise resolves.

一开始可能很难理解，但它是与传统AJAX请求非常相似 - 您在回调中处理响应。

It can be hard to get your head around at first, but it's much the same as a "traditional" AJAX request - you handle the response in a callback.

举个例子：

var x = fetch(SOME_URL, SOME_POST_DATA)
    .then((response) => response.json())
    .then((responseJSON) => {
       // do stuff with responseJSON here...
       console.log(responseJSON);
    });

更多阅读： https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

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