record.js

records.js

// https://github.com/muaz-khan/RecordRTC
/*
<!-- recommended -->
<script src="https://www.WebRTC-Experiment.com/RecordRTC.js"></script>

<!-- use 5.6.2 or any other version on cdnjs -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/RecordRTC/5.6.2/RecordRTC.js"></script>

<!-- NPM i.e. "npm install recordrtc" -->
<script src="node_modules/recordrtc/RecordRTC.js"></script>
*/

navigator.mediaDevices.getUserMedia({
    video: false,
    audio: true
}).then(async function(stream) {
    let recorder = RecordRTC(stream, {
        type: 'video'
    });
    recorder.startRecording();

    const sleep = m => new Promise(r => setTimeout(r, m));
    await sleep(3000);

    recorder.stopRecording(function() {
        let blob = recorder.getBlob();
        invokeSaveAsDialog(blob);
        console.log(blob)
    });
});