javascript - 在 Chrome 扩展程序中创建自定义 header 失败

Question

这个问题已经有答案了:

Trying to use fetch and pass in mode: no-cors (12 个回答)

已关闭 4 年前。

我尝试为以下 fetch() 创建一个 header ，如下所示

var myheaders = new Headers(
   { "Accept": "application/json",
     "Content-Type": "application/json; charset=UTF-8"
   });

let b = JSON.stringify ({ "cmd2" : "ytdl", "url" : "x"});

let params = 
{ headers : myheaders,
  body : b,
  method : "POST",
  mode : "no-cors"
};
let response = await fetch("http://127.0.0.1:5000/ytdl",params);
....

如果我在接收服务器(Flask)中打印标题，我会得到:

Host: 127.0.0.1:5000
Connection: keep-alive
Content-Length: 67
Accept: application/json
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6)        AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36
Sec-Fetch-Mode: no-cors
Content-Type: text/plain;charset=UTF-8
Origin: chrome-extension://mnihgjnpmkpgeichhdfhejagbefjpnnb
Sec-Fetch-Site: cross-site
Accept-Encoding: gzip, deflate, br
Accept-Language: de-DE,de;q=0.9,en-US;q=0.8,en;q=0.7

有什么想法吗，我做错了什么？

Answer 1

我不明白原因是什么，但是当您在没有 mode: 'no-cors' 的情况下调用时，内容类型是:

let params = {
  headers : myheaders,
  body : b,
  method : "POST",
  mode : "cors"
};

response = await fetch("http://127.0.0.1:5000/", params);

flask 的输出request.headers:

...
Accept: application/json
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36
Sec-Fetch-Mode: cors
Content-Type: application/json; charset=UTF-8
...