Greasemonkey script: Record Local Audio in Jitsi Meet

record_audio.js

// ==UserScript==
// @name         Record local audio in Jitsi Meet
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://meet.jit.si/*
// @grant        none
// ==/UserScript==

(function () {
    'use strict';

    var myAudioStream = null;
    var mediaRecorder = null;

    navigator.getUserMedia(
        // constraints - only audio needed for this app
        {
            audioBitsPerSecond: 256000, //256 kbps
            audio: true,
            mimeType: 'audio/wav' // is it really wav? need to figure out
        },
        // Success callback
        (stream) => {
            myAudioStream = stream;
            mediaRecorder = new MediaRecorder(stream);
            mediaRecorder.ondataavailable = e => {
                console.log("data available");
                var audioURL = window.URL.createObjectURL(e.data);
                console.log("Audio URL:", audioURL);

                // auto save audio
                var a = document.createElement("a");
                document.body.appendChild(a);
                a.style = "display: none";
                a.href = audioURL;
                a.download = "recording.wav";
                a.click();
            };
        },

        // Error callback
        (err) => {
            console.log('The following gUM error occurred: ' + err);
        }
    );

    // set up UI
    var toggleButton = document.createElement("div");
    toggleButton.innerText = "Record";
    toggleButton.style = "background: gray; width: 100px; height: 50; position: absolute; top: 10px; right: 10px; z-index: 10000;";

    var state = 'idle';
    toggleButton.onclick = (e) => {
        switch (state) {
            case 'idle':
                toggleButton.innerText = 'Stop';
                toggleButton.style.backgroundColor = 'red';
                mediaRecorder.start();
                state = 'recording';
                break;
            case 'recording':
                toggleButton.innerText = 'Record';
                toggleButton.style.backgroundColor = 'gray';
                mediaRecorder.stop();
                state = 'idle';
                break;
            default:
                break;
        }
    };

    document.body.appendChild(toggleButton);

})();