当json解析一个空响应时，Whatwg Fetch失败，如何防止它? [英] Whatwg Fetch fails when json parsing an empty response, how can I prevent it?

问题描述

我在前端和后端(NodeJS)上都使用Fetch API，将响应解析为json时，我经常遇到的一个问题.

I'm using the Fetch API both in the frontend and on the backend (NodeJS), a problem that I've been facing a lot happens when parsing the response as json.

response.json()将返回一个Promise，因此我事先不知道响应的主体是什么，当主体为空时，JSON解析将失败，并显示以下错误:

response.json() will return a promise so I don't know beforehand what the body of the response is, and when the body is empty the JSON parsing will fail with the error:

SyntaxError: Unexpected end of input

所以我的问题是，如何防止在响应为空时对其进行解析?

So my question is, how to prevent parsing the response when its empty?

谢谢

推荐答案

一旦有了Response对象，请检查标题并查看Content-Length的内容.基于此，您可以知道是否有要解析的内容.但是，服务器返回一个空的application/json资源似乎是伪造的，因为它不是JSON.

Once you have the Response object, inspect the headers and see what Content-Length says. Based on that you can know whether or not there is something to parse. But also, it seems bogus for the server to return an application/json resource that is empty, as that is not JSON.

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