Tampermonkey script to set YouTube playback speed to 2x

2xYT.js

// ==UserScript==
// @name         2xYT
// @version      0.1
// @description  Automatically sets the playback speed to 2x on YouTube.com
// @match        *://www.youtube.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const playbackSpeedSettingsKey = 'yt-player-playback-rate';

    // Check if already 2x
    if(!(playbackSpeedSettingsKey in sessionStorage) || JSON.parse(sessionStorage[playbackSpeedSettingsKey]).data != 2){
        const playbackSpeedSettings = { 'data':'2', 'creation': Date.now() };
        sessionStorage[playbackSpeedSettingsKey] = JSON.stringify(playbackSpeedSettings);
        // Reload to apply changed settings
        location.reload();
    }
})();