Turn off/disable YouTube autoplay feature

disable_youtube_autoplay.user.js

// To run, install GreaseMonkey or TamperMonkey extension in your browser
// Copy this code into new user script, and enable

// ==UserScript==
// @name         Disable Youtube autoplay
// @version      2.0
// @description  This script turns off Youtube's autoplay feature after the page loads. This is permanent, you hit the button, it'll forced to be off.
// @author       Jeff Bellucci & bitelaserkhalif
// @match        *://www.youtube.com/*
// @run-at       document-idle
// @grant        none
// @require      https://code.jquery.com/jquery-3.6.0.min.js

// ==/UserScript==
/* globals $ */

(function() {

    'use strict';
    var intervalID = window.setInterval(disableAfterLoad, 500);

    function disableAfterLoad() {
        var autoplayToggle = $("#movie_player").find('.ytp-autonav-toggle-button').attr('aria-checked');
        if (autoplayToggle == 'true') {
            $("#movie_player").find('.ytp-autonav-toggle-button').trigger( "click" );
            console.log('disabled: '+ autoplayToggle);
        } else {
            if (autoplayToggle == 'false') {
                clearInterval(disableAfterLoad);
            }
            setTimeout(disableAfterLoad, 500);
        }
    }

    disableAfterLoad();
})();

Updated with JQuery because youtube kept breaking stuff. (You refresh the page, autoplay goes back on even if you turn it off.)

Thank you so much. Finally I don't have to toggle autoplay off every time I open a new YouTube tab.

I dunno why YouTube breaks shit like this, autoplay for me stayed off for months if not years.

Thanks brother. It drove me crazy.

Welp, I guess youtube fixed that problem.
But this extension is useful for incognito/no sign in.