web-youtube-live-chat-script.js

var messageHistory = []; var els = document.body.querySelectorAll('yt-live-chat-text-message-renderer'); Array.from(els).filter(el => Array.from(messageHistory).filter(message => message.getAttribute('id') === el.getAttribute('id')).length === 0).map(el => { messageHistory.push(el); return el.querySelector('#message').textContent });
var messageHistory = [];
var src = 'http://static.junmakii.umu.us/bell.ogg';
var audioEl = document.createElement('audio');
audioEl.setAttribute('src', src);  

let play = function () {
    let el = audioEl.cloneNode(true);
    el.play();
};

let interval = function () {
    try {
        var els = document.body.querySelectorAll('yt-live-chat-text-message-renderer');
        els = Array.prototype.slice.call(els, els.length - 10, els.length);
        var doPlay = !!messageHistory.length
        Array.from(els)
                                     .filter(el => Array.from(messageHistory).filter(message => message.getAttribute('id') === el.getAttribute('id')).length === 0)
                                     .map(el => {
                                         if (messageHistory.length > 10) { messageHistory.shift(); }
                                         messageHistory.push(el);
                                         if (doPlay) { play()
                                             new Notification(
                                                 'YouTube Live',
                                                 {"body": el.querySelector('#author-name').textContent + ' : ' + el.querySelector('#message').textContent })
                                         };
                                     });
    } catch (err) {
        console.error(err);
    }
};

let main = function () {
    // el.addEventListener('loadeddata', () => el.play())
    if (Notification.permission !== 'granted') { Notification.requestPermission(permission => permission) }
    
    window.setTimeout(() => { window.setInterval(interval, 5000, false) }, 1000);
};

main();