How to record audio from the user's microphone

François Beaufort

Accessing the user's camera and microphone is possible on the web platform with the Media Capture and Streams API. The getUserMedia() method prompts the user to access a camera and/or microphone to capture as a media stream. This stream can then be recorded with the MediaRecorder API or shared with others over the network. The recording can be saved to a local file via the showOpenFilePicker() method.

The example below shows how you can record audio from the user's microphone in the WebM format and save the recording to the user's file system.

let stream;
let recorder;

startMicrophoneButton.addEventListener("click", async () => {
  // Prompt the user to use their microphone.
  stream = await navigator.mediaDevices.getUserMedia({ audio: true });
  recorder = new MediaRecorder(stream);
});

stopMicrophoneButton.addEventListener("click", () => {
  // Stop the stream.
  stream.getTracks().forEach(track => track.stop());
});

startRecordButton.addEventListener("click", async () => {
  // For the sake of more legible code, this sample only uses the
  // `showSaveFilePicker()` method. In production, you need to
  // cater for browsers that don't support this method, as
  // outlined in https://web.dev/patterns/files/save-a-file/.

  // Prompt the user to choose where to save the recording file.
  const suggestedName = "microphone-recording.webm";
  const handle = await window.showSaveFilePicker({ suggestedName });
  const writable = await handle.createWritable();

  // Start recording.
  recorder.start();
  recorder.addEventListener("dataavailable", async (event) => {
    // Write chunks to the file.
    await writable.write(event.data);
    if (recorder.state === "inactive") {
      // Close the file when the recording stops.
      await writable.close();
    }
  });
});

stopRecordButton.addEventListener("click", () => {
  // Stop the recording.
  recorder.stop();
});