GreaseMonkey script to add a button to clone a test plan in Azure DevOps

CloneTestPlan.user.js

// ==UserScript==
// @name     CloneTestPlan
// @description     Azure DevOps Clone Test Plan Button
// @match    https://dev.azure.com/*/*/_testManagement?planId=*
// @version  1.0
// @run-at   document-end
// @grant    unsafeWindow
// ==/UserScript==

function cloneTestPlan() {
  const { XMLHttpRequest, console, decodeURIComponent, document, location } = unsafeWindow;
	const urlFrags = ("" + location).split('/').slice(0, 5);
	const baseUrl = urlFrags.join('/');
	const apiUrl = urlFrags.concat([ "_apis/testplan/Plans/CloneOperation?deepClone=true&api-version=5.1-preview.2" ]).join('/');
  const breadCrumbs = document.querySelectorAll('.vss-Breadcrumb li .vss-Breadcrumb--itemText');
  const name = breadCrumbs && breadCrumbs.length && breadCrumbs[breadCrumbs.length-1].innerText;
  const args = (location.search.length <= 1) ? {} :
  	location.search.substring(1).split('&').reduce((a, p) => {
      let halves = p.split('=');
      a[decodeURIComponent(halves[0])] = decodeURIComponent(halves[1]);
      return a;
    }, {});
  const body = {
    cloneOptions: {
      copyAllSuites: true,
      copyAncestorHierarchy: true
    },
    destinationTestPlan: {
      name: "Clone of " + name
    },
    sourceTestPlan: {
      id: args.planId
    }
  };
  //console.log("#####################", apiUrl, body);
  var xhr = new XMLHttpRequest();
  xhr.open("POST", apiUrl, true);
  xhr.setRequestHeader('Content-type', 'application/json; charset=UTF-8');
  //xhr.onreadystatechange = console.log;
  xhr.send(JSON.stringify(body));
}

window.setTimeout(function(win) {
  const doc = win.document;
  const parent = doc.querySelector('.vss-HubHeader');
  const button = doc.createElement("button");

  button.innerText = "Clone";
  parent.insertBefore(button, parent.firstChild);
  button.addEventListener("click", cloneTestPlan);
}, 3000, window);