// ==UserScript==
// @name         New Userscript
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://www.baidu.com/*
// @run-at       document-start
// @grant        unsafeWindow
// ==/UserScript==

(function() {
    'use strict';
    unsafeWindow.moref = unsafeWindow.MutationObserver;

    document.addEventListener('DOMContentLoaded', function(){
        console.log("overridden mutation oberver:");
        console.log(unsafeWindow.MutationObserver);

        console.log("original mutation oberver:");
        console.log(unsafeWindow.moref);
    });
})();