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YouTube Dark Theme Enabler

Enables YouTube's built-in Dark theme by default

// ==UserScript==
// @name         YouTube Dark Theme Enabler
// @namespace    https://violentmonkey.github.io/
// @version      1.0
// @description  Enables YouTube's built-in Dark theme by default
// @author       Streampunk
// @icon         data:image/png;base64,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
// @match        https://www.youtube.com/*
// @grant        none
// @run-at       document-start
// @license      MIT
// ==/UserScript==

// Check if there's PREF special cookie, that enables the Dark Theme
if (document.cookie.split('&').filter((item) => item.includes('PREF=f6=400')).length) {
// console.log('Cookie for Dark Theme already exists')
} else {
// If there's no special cookie, then create one with a value that enables the Dark Theme
  document.cookie = "PREF=f6=400;domain=youtube.com";
// Reload the page so that the changes take effect immediately
  location.reload();
}