Replace All Text with "?"

Replaces all text on a website with "?"

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// ==UserScript==
// @name         Replace All Text with "?"
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Replaces all text on a website with "?"
// @author       UnknownQwertyz
// @match        *://*/*
// @license      MIT
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

//script running?
function scriptRunning() {
    document.getElementById("logo").src = "https://content.presentermedia.com/files/clipart/00001000/1680/stickman_question_mark_thinking_pc_800_wht.png"
};


window.onload = function () {
    document.title = "‏‏‎ ‎";
};


const newLogo = "https://content.presentermedia.com/files/clipart/00001000/1680/stickman_question_mark_thinking_pc_800_wht.png";

setTimeout(() => {
  const logo = document.querySelector("img");
  if (logo) {
    logo.src = newLogo;
  }
}, 2000);


const observer = new MutationObserver(mutations => {

  mutations.forEach(mutation => {

    const added = mutation.addedNodes;

    if (added && added.length > 0) {

      try {

        const logo = added[0].querySelector("img");

        if (logo) {
          logo.src = newLogo;
        }

      } catch (err) {
        // Ignore selector error
      }

    }

  });

});
    // Select all text nodes on the page
    const walker = document.createTreeWalker(
        document.body,
        NodeFilter.SHOW_TEXT,
        null,
        false
    );

    let node;
    while (node = walker.nextNode()) {
        node.nodeValue = "?";
    }
})();