Geordle Date Spoofer.user.js

// ==UserScript==
// @name         Geordle Date Spoofer
// @namespace    geordle-fake-date
// @version      1
// @match        https://no-jons.xyz/geordle*
// @match        http://no-jons.xyz/geordle*
// @grant        unsafeWindow
// @run-at       document-start
// ==/UserScript==

// https://stackoverflow.com/a/35385518
function fromHTML(html, trim = true) {
  // Process the HTML string.
  html = trim ? html.trim() : html;
  if (!html) return null;

  // Then set up a new template element.
  const template = document.createElement('template');
  template.innerHTML = html;
  const result = template.content.children;

  // Then return either an HTMLElement or HTMLCollection,
  // based on whether the input HTML had one or more roots.
  if (result.length === 1) return result[0];
  return result;
}


if(unsafeWindow.location.hash) {
    // Specify the fake date and time you want to use
    const fakeDate = new Date(unsafeWindow.location.hash.substring(1).slice(0, 10) + "T00:00:00");

    // Override the global Date object with a custom FakeDate class
    class FakeDate extends Date {
        constructor() {
            super();
            return fakeDate;
        }
    }

    unsafeWindow.Date = FakeDate;
}

unsafeWindow.changeDate = function() {
    let entry = prompt("Enter the desired date in format YYYY-MM-DD:");
    entry = entry.slice(0, 10);

    let vaildate = new Date(entry).toISOString().slice(0, 10);

    if(entry == vaildate) {
        window.location = location.pathname + "#" + entry;
        unsafeWindow.location.reload();
    }
}

let game = document.getElementById("game");
let button = fromHTML("<button style='position:absolute;z-index: 1000' onclick='changeDate()'>" + new unsafeWindow.Date().toISOString().slice(0, 10) + "</button>");
document.body.append(button);