Add a "Copy link" button to Github issue and pull requests

github.js

// ==UserScript==
// @name         Copy Link for GitHub Issues and PRs
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Add a "Copy link" button to Github issue and pull requests
// @author       ye11ow, K8sCat <k8scat@gmail.com>
// @match        https://github.com/*
// @include      https://github.com/*/issues/*
// @include      https://github.com/*/pull/*
// @icon         https://www.google.com/s2/favicons?domain=github.com
// @grant        none
// ==/UserScript==

(function () {
  "use strict";

  function capitalize(word) {
    const lower = word.toLowerCase();
    return lower.charAt(0).toUpperCase() + lower.slice(1);
  }

  function add() {
    if (!document.querySelector(".gh-header-actions")) {
      return;
    }
    const copyBtn = document.createElement("button");
    copyBtn.innerText = "Copy link";
    copyBtn.classList.add("btn");
    copyBtn.classList.add("btn-sm");
    copyBtn.style.marginRight = "8px";

    copyBtn.addEventListener("click", () => {
      const title = capitalize(
        document.querySelector(".js-issue-title.markdown-title").innerText
      );
      const number = capitalize(
        document.querySelector(".f1-light.color-fg-muted").innerText
      )
      const paths = location.pathname.split("/");
      if (paths.length < 5) {
        return;
      }

      const project = capitalize(paths[2]);
      const id = paths[4];

      const textBlob = new Blob([`${number} ${title} ${location.href}`], { type: "text/plain" });
      const htmlBlob = new Blob(
        [`${title} [<a href="${location.href}">${project}#${id}</a>]`],
        { type: "text/html" }
      );
      const data = new ClipboardItem({
        "text/plain": textBlob,
        "text/html": htmlBlob,
      });

      navigator.clipboard.write([data]);
    });

    document.querySelector(".gh-header-actions").prepend(copyBtn);
  };

  add();
})();