12_custom.js

// [...]
recording.addEventListener("pointerup",  async () => {
    // Stop the recording
    recorder.state == "recording" && recorder.stop()

    recordedChunks = await recordedChunks
    recordedBlob = new Blob(recordedChunks, {type: 'audio/ogg; codecs="opus"'});

    // Create an audio file
    var audioFile = new File([recordedBlob], "audio.ogg", {
        type: 'audio/ogg; codecs="opus"',
    });

    // Send the recorded file to Stream CDN
    response = await channel.sendFile(
        audioFile,
        'audio.ogg',
    )
   
    const attachments = [{
        type: 'file',
        thumb_url: response.file,
        asset_url: response.file,
    }]
    
    // Send the attachment to the channel
    sendMessage("", attachments)
})