grim.reaper.slave / YTB to Embed window

// ==UserScript==
// @name           YTB to Embed window
// @namespace      http://fb.com/grim.reaper.slave
// @version        0.2
// @copyright      2017+ Đặng Quốc Trung (MarkiThePews)
// @description    A personal script for meh, but someone might need it!
// @include        *.youtube.com/watch*
// @include        *.youtube.com/embed*
// @homepageURL    http://fb.com/grim.reaper.slave
// @updateURL https://openuserjs.org/meta/grim.reaper.slave/YTB_to_Embed_window.meta.js
// @author         Đặng Quốc Trung
// ==/UserScript==

// Last updated on 2017-03-30 (YYYY-MM-DD)
function tohopphim(e) {
      var evtohop = window.event? event : e;
      if (evtohop.keyCode == 88 && evtohop.ctrlKey) changeitman();
}

document.onkeydown = tohopphim;

function changeitman() {
    var kiemtra = window.location.href;
    substring = "watch";
    var ketqua = kiemtra.includes(substring);
    if (ketqua) changetoembed(); else changetonm();
}
function changetoembed() {
var s = window.location.href;
s = s.replace("watch?v=", "embed/");
window.location.replace(s);
}
function changetonm() {
var s = window.location.href;
s = s.replace("embed/", "watch?v=");
window.location.replace(s);
}