请求已被 CORS 策略阻止，无法访问后端

Question

我收到此错误 has been blocked by CORS policy: Response to preflight request doesn't pass access control check: Redirect is not allowed for a preflight request，我知道这个问题已被问过很多次，但尝试了所有这些问题，但没有一个对我有用。我的问题是我无法访问后端并尝试下载 chrome 扩展来修复它，但它不起作用。当我在终端中运行没有 HTML 文件的代码时，我可以获得数据并且它工作正常，但是当我将 JS 文件与 HTML 文件连接时会出现问题。下面是我的 JS 代码。

let base64 = require("base-64");
const fetch = require("node-fetch");
const https = require("https");
let url = "some url";
let username = "username";
let password = "password";

let headers = new fetch.Headers();
const agent = new https.Agent({
  rejectUnauthorized: false,
});
headers.set(
  "Authorization",
  "Basic " + base64.encode(username + ":" + password)
);

const res = fetch(url, {
  agent,
  method: "GET",
  headers: headers,
}).then((response) => response.json());

res
  .then(function (result) {
    console.log(result);
  })
  .catch((err) => {
    console.log(err);
  });