fetch for UserScript

using fetch based on GM.xmlHttpRequest in userscript.

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

Introduction

It's not 100% same with fetch API because some security limit like cors site request doesn't exist on GM.xmlHttpRequest.

And AbortSignal is not supported very well due to the limitation of GM.xmlHttpRequest.

You can set some HTTP headers allowed by GM.xmlHttpRequest but not allowed by standard fetch API.

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/gm-fetch@0.1.15)

if you are using js bundler

ES Module:

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

CommonJS (not recommended):

const GM_fetch = require("@trim21/gm-fetch");

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