Hide live chat by default on YouTube live streams

hide_live_chat.js

// ==UserScript==
// @name         YouTube - Hide Live Chat
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Hide live chat by default on live streams
// @author       LM
// @match        https://www.youtube.com/watch*
// @run-at       document-end
// @grant        none
// ==/UserScript==

function AddClass() {
    var el = document.getElementById("live-chat-iframe");
    if(el) {
        el.parentElement.classList.add("yt-uix-expander-collapsed");
        console.log('Hide Live Chat');
        return true;
    }
    return false;
}

function KeepTrying(func, attempts, delay) {
    console.log('Keep Trying ' + attempts);
    if( !func() && attempts-1 > 0 ) {
        window.setTimeout( function() {
            KeepTrying(func, attempts-1, delay);
        });
    }
}

(function() {
    'use strict';

    KeepTrying( AddClass, 5, 10 );

})();

It's one problem... It's add new chat after resize (cause there are different for desktop and mobile), sow you need to register keep trying in resize event window.addEventListener('resize', KeepTrying(PressHideButton, 12, 200));

Based off @milroneth's version with following improvements:

• Avoid opening live chat if it's closed by default (premiered video pages).
• Works when navigating to YouTube watch page from another YouTube page, which involves AJAX rather than new page load, via polling for URL changes and watching all non-embed YouTube pages.

// ==UserScript==
// @name         YouTube - Hide Live Chat
// @namespace    https://gist.github.com/LazyMammal/1c60c45e9df26602f688d025f3b20f0c#gistcomment-3656586
// @version      0.4
// @description  Hide live chat by default on live streams
// @author       LM, bastiMQ, IrisNebula, lbmaian
// @match        https://www.youtube.com/*
// @exclude      https://www.youtube.com/embed/*
// @run-at       document-end
// @grant        none
// @icon         https://www.youtube.com/favicon.ico
// ==/UserScript==

function log(str) {
	console.log('[YouTube - Hide Live Chat] ' + str);
}

function pressHideButton() {
	var el = document.getElementById('chat');
	if(el) {
		if(el.hasAttribute('collapsed')) {
			log('Live Chat already hidden');
			return true;
		} else {
			el = document.getElementById('show-hide-button');
			if(el) {
				while(el.children.length > 0) {
					if(el.firstChild.getAttribute('id') == 'button') {
						el.firstChild.click();
						log('Live Chat hidden');
						return true;
					}
					el = el.firstChild;
				}
			}
		}
	}
	return false;
}

function keepTrying(func, attempts, delayMillis) {
	log('Trying to hide Live Chat, remaining attempts: ' + attempts);
	if(!func() && (attempts-1 > 0)) {
		window.setTimeout(function() {
			keepTrying(func, attempts-1, delayMillis);
		}, delayMillis);
	}
}

function checkForWatchPage(url) {
	if(url.startsWith('https://www.youtube.com/watch')) {
		log('Matched ' + url);
		keepTrying(pressHideButton, 12, 200);
	}
}

(function() {
	'use strict';

	// Navigating to YouTube watch page can happen via AJAX rather than new page load, so keep polling for URL changes.
	// This also requires watching all YouTube pages, rather than just watching https://www.youtube.com/watch*
	var curURL = document.URL;
	window.setInterval(function() {
		var newURL = document.URL;
		if(curURL != newURL) {
			curURL = newURL;
			checkForWatchPage(curURL);
		}
	}, 500);

	checkForWatchPage(curURL);
})();

I'd love to see this as a repo so updates can be automatically received via a userscript manager.

Continuing this in https://gist.github.com/lbmaian/94824cef728917a53d3c6e6ea885469c