Tampermonkey Script – Auto Image Conversion for GitHub

github-image-markdown-auto-resize.user.js

// ==UserScript==
// @name         GitHub Auto Image Markdown to <img>
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Auto-convert uploaded GitHub image markdown to <img> with width=200 (for PRs, issues, comments)
// @match        https://github.com/*
// @grant        none
// ==/UserScript==

(function () {
  'use strict';

  const imageMarkdownRegex = /!\[([^\]]*?)\]\((https:\/\/(?:user-images\.githubusercontent\.com|github\.com\/user-attachments\/assets)\/[^\)]+)\)/g;

  function convertMarkdownToImg(textarea) {
    if (!textarea || !textarea.value) return;

    const original = textarea.value;

    const converted = original.replace(
      imageMarkdownRegex,
      (_match, alt, url) => `<img src="${url}" alt="${alt}" width="200" />`
    );

    if (converted !== original) {
      textarea.value = converted;
    }
  }

  function checkAllTextareas() {
    const textareas = document.querySelectorAll('textarea');
    textareas.forEach(convertMarkdownToImg);
  }

  // Check every second to catch uploads
  setInterval(checkAllTextareas, 1000);

  console.log("✅ GitHub image conversion script running.");
})();