问题描述

当我们在 JS 中使用 fetch 发出 get 请求时，我们通常会这样做

when we use fetch in JS to issue a get request, we normally do thing like this

fetch(endpoint).then(res => res.json()).then(result => ...)

但是，我正在观看 Wes Bos 的 JS 30 课程，他称中间结果为 fetch 返回一个 blob，如

However I was watching Wes Bos's JS 30 courses and he called the intermediate result that the fetch returns a blob as in

fetch(endpoint).then(blob => blob.json()).then(result => ...)

我在这里找到了 blob 的定义 https://developer.mozilla.org/en-US/docs/Web/API/Blob

I found the definition for blob here https://developer.mozilla.org/en-US/docs/Web/API/Blob

我没有足够的知识来判断 Wes Bos 是否在这里使用了正确的术语来将其称为 blob，我无法直接联系他并询问他.希望我能在这里找到一些答案.

I am not knowledgable enough to judge if Wes Bos was using the right term here to refer to it as blob and I have no ways to contact him directly and ask him. Hope I can find some answers here.

推荐答案

fetch 返回一个 Response 对象，而不是 Blob - 如果您尝试使用像 .slice 和 .stream 结果会抛出错误，因为这些方法不存在.

fetch returns a Response object, not a Blob - if you try to use blob methods like .slice and .stream on the result, errors will be thrown, since those methods do not exist.

// Not OK:
fetch('data:,Hello%2C%20World!').then(blob => blob.slice()).catch((err) => console.log('err', err.message));
// OK:
fetch('data:,Hello%2C%20World!').then(res => res.text()).then(console.log);

请注意，响应可以转换为 Blob，但 fetch 的返回值仍然是响应:

Note that the Response can be converted into a Blob, but the return value from fetch would still be a Response:

fetch(endpoint)
  .then(response => response.blob())
  .then((blob) => {
    // work with the blob here
  });

将响应称为 blob 是不正确的.它们有些相似，但又不一样.最好避免将其称为 blob 以避免混淆.

Calling the response a blob is incorrect. They're somewhat similar, but not the same. Better to avoid calling it a blob to avoid confusion.

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