fetch for UserScript

using fetch based on GM.xmlHttpRequest in userscript.

Don't forget to add @grant GM.xmlHttpRequest and @connect in your metadata

Example

add this script to UserScript manager and visit https://example.com/

// ==UserScript==
// @name        new user script
// @version     0.0.1
// @match       https://example.com/*
// @grant       GM.xmlHttpRequest
// @require     https://cdn.jsdelivr.net/npm/@trim21/gm-fetch
// @run-at      document-end
// @connect     httpbin.org
// ==/UserScript==

(async () => {
  const res = await GM_fetch("https://httpbin.org/headers", { method: "GET" });
  const data = await res.json();
  console.log(data);
})();

(you can't use @require https://cdn.jsdelivr.net/npm/@trim21/gm-fetch directly if you want to upload your script to GreasyFork, you will need to specify version you want to use, for example @require https://cdn.jsdelivr.net/npm/@trim21/[email protected])

if you are using js bundler

ES Module:

import GM_fetch from "@trim21/gm-fetch";

Compatibility Differences

This library provides a fetch API based on GM.xmlHttpRequest.

It do not behave 100% same as the standard fetch API, because some security limitations like CORS site requests don't exist on GM.xmlHttpRequest.

Key Differences:

• AbortSignal: Not fully supported due to the limitations of GM.xmlHttpRequest
• CORS: Cross-origin requests work without CORS restrictions, unlike standard fetch
• HTTP Headers: You can set some HTTP headers that are allowed by GM.xmlHttpRequest but not allowed by standard fetch API
• Redirect Parameter: The redirect parameter 'follow' | 'error' | 'manual' is not supported. All redirects are automatically followed by GM.xmlHttpRequest, similar to redirect: 'follow' behavior

Browser Compatibility

This package is using Request and Response class, it so requires a browser with fetch API support.

https://caniuse.com/?search=Blob.stream

Licence

MIT