fetch().then() 返回内容类型和正文

fetch().then() return content-type and body(fetch().then() 返回内容类型和正文)

问题描述

互联网上的每个 fetch API 示例都展示了如何使用 response.json()、response.blob() 等仅返回正文.我需要的是调用一个同时具有内容类型和主体作为 blob 的函数，但我不知道该怎么做.

Every fetch API example on the internet shows how to return only the body using response.json(), response.blob() etc. What I need is to call a function with both the content-type and the body as a blob and I cannot figure out how to do it.

fetch("url to an image of unknown type")
  .then((response) => {
    return {
      contentType: response.headers.get("Content-Type"),
      raw: response.blob()
  })
  .then((data) => {
    imageHandler(data.contentType, data.raw);
  });

这显然不起作用:data.contentType 已填充，但 data.raw 是一个承诺.如何在同一上下文中获取这两个值?

This obviously doesn't work: data.contentType is filled, but data.raw is a promise. How can I get both values in the same context?

推荐答案

你可以这样写:

fetch("url to an image of unknown type")
  .then(response => {
    return response.blob().then(blob => {
      return {
        contentType: response.headers.get("Content-Type"),
        raw: blob
      }
    })
  })
  .then(data => {
    imageHandler(data.contentType, data.raw);
  });

或者这样

fetch("url to an image of unknown type")
  .then(response => {
    return response.blob().then(blob => {
        imageHandler(response.headers.get("Content-Type"), blob)
    })
  })

在这两种情况下，您都将收到已解析的 blob 的回调保留在您有权访问 response 的范围内.

In both cases you keep the callback in which you receive the resolved blob within the scope where you have access to response.

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