Add a Button for the Github page to open in https://blocks.githubnext.com

github-blocks.js

// ==UserScript==
// @name         Gitbub Blocks
// @namespace    https://github.com/
// @version      1.0
// @description  Add a button to replace github.com with block.githubnext.com in the URL bar on GitHub repositories page
// @author       https://twitter.com/stackobserve
// @match        https://github.com/*/*
// @grant        window.onurlchange
// ==/UserScript==

if (window.onurlchange === null) {
  // feature is supported
  window.addEventListener("urlchange", inject);
}

function inject({ url }) {
  // console.log("inject", url);
  const url_segments = url.split("/");
  if (url_segments.length < 5) return;
  const container = document.querySelector("ul.pagehead-actions");
  if (container === null) {
    return console.warn(
      "[GithubBlocks] query is invalid: ul.pagehead-actions is not found"
    );
  }
  const [user, repo, ...paths] = url_segments.slice(3);
  if (paths[0] === "tree") paths[0] = "blob";
  const path = paths.join("/");
  const next_url = `https://blocks.githubnext.com/${user}/${repo}/${path}`;
  render(container, next_url);
}
function render(parent, url) {
  const newInnerHTML = `<a id='__gm_blocks' class="btn-sm btn BtnGroup-item" href="${url}">Blocks</a>`;
  let target = document.getElementById("__gm_blocks");
  if (target === null) {
    const li = document.createElement("li");
    li.innerHTML = newInnerHTML;
    parent.insertBefore(li, parent.firstChild);
    target = li.children.item(0);
  } else {
    target.parentElement.innerHTML = newInnerHTML;
  }
}