Browser based audio output recorder

README.md

HOW TO USE

1. copy and paste the code to browser console
2. run record(); to record audio output
3. run stop(); to stop recording
4. run download() to download last recording

recordAudioOutput.js

let recorder;
let recordedChunks = [];

function dataAvailable(event) {
    if (event.data.size > 0) {
        recordedChunks.push(event.data);
    }
}

function resetState() {
    recorder = null;
    recordedChunks = [];
}

function download() {
    let blob = new Blob(recordedChunks, {
        type: "audio/aac",
    });
    let url = URL.createObjectURL(blob);
    let a = document.createElement("a");
    document.body.appendChild(a);
    a.style = "display: none";
    a.href = url;
    a.download = `${new Date().toISOString()}.webm`;
    a.click();
    window.URL.revokeObjectURL(url);
    resetState();
}
async function record() {
    let stream = await navigator.mediaDevices.getUserMedia({
        audio: true,
        video: true
    });
    stream.getVideoTracks().forEach((x) => x.stop());
    stream.getAudioTracks().forEach((x) => x.stop());
    const devices = await navigator.mediaDevices.enumerateDevices();
    console.log(devices);
    const firstAudioOutput = devices.find((device) => {
        return device.kind === "audiooutput"
    });
    stream = await navigator.mediaDevices.getUserMedia({
        audio: {
            deviceId: {
                exact: firstAudioOutput.deviceId
            }
        }
    });
    recorder = new MediaRecorder(stream);
    recorder.start();
    recorder.addEventListener("stop", download);
    recorder.addEventListener("dataavailable", dataAvailable);
}

function stop() {
    recorder.stop();
}