Record video + audio from a browser tab/window/screen

media-recorder.js

const media = await navigator.mediaDevices.getDisplayMedia({
  audio: {
    echoCancellation: false,
    autoGainControl: false,
    noiseSuppression: false,
  },
})

const recorder = new MediaRecorder(media, {
  mimeType: 'video/webm',
})
recorder.ondataavailable = (event) => {
  event.data.stream().pipeTo(writableStream)
}
recorder.start()

const fileHandle = await window.showSaveFilePicker({
  startIn: 'desktop',
  suggestedName: 'output.webm',
})
const writableStream = await fileHandle.createWritable()

// recorder.requestData()
// recorder.stop()