Rotate YouTube videos Tampermonkey script

rotate-youtube.tamper.js

// ==UserScript==
// @name         Rotate YouTube
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Key bindings to rotate youtube videos
// @author       osuushi
// @match        https://www.youtube.com/watch?*
// @icon         https://www.google.com/s2/favicons?domain=youtube.com
// @grant        GM_addStyle
// @require      https://cdnjs.cloudflare.com/ajax/libs/mousetrap/1.6.5/mousetrap.min.js
// ==/UserScript==

(function() {
  'use strict';
  let oldStyle = null
  let angle = 0

  const updateStyle = () => {
    if (oldStyle) oldStyle.remove()
    let scale = 1
    if (angle % 180 != 0) {
      scale = 10/16
    }
    oldStyle = GM_addStyle(`
      video {
        transition: transform 400ms;
        transform: rotate(${angle}deg) scale(${scale});
      }
    `)
  }

  Mousetrap.bind("alt+,", () => {
    angle -= 90
    updateStyle()
  })

  Mousetrap.bind("alt+.", () => {
    angle += 90
    updateStyle()
  })
})();