How to record the user's screen

François Beaufort

Sharing tabs, windows, and screens is possible on the web platform with the Screen Capture API. The getDisplayMedia() method allows the user to select a screen 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 the user's screen in the WebM format, locally preview on the same page, and save the recording to the user's file system.

let stream;
let recorder;

shareScreenButton.addEventListener("click", async () => {
  // Prompt the user to share their screen.
  stream = await navigator.mediaDevices.getDisplayMedia();
  recorder = new MediaRecorder(stream);
  // Preview the screen locally.
  video.srcObject = stream;
});

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

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 = "screen-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();
});