Cómo grabar la pantalla del usuario

François Beaufort
François Beaufort
GitHub

Es posible compartir pestañas, ventanas y pantallas en la plataforma web con la API de Screen Capture. El método getDisplayMedia() permite al usuario seleccionar una pantalla para capturar como transmisión multimedia. Luego, podrás grabar esta transmisión con la API de MediaRecorder o compartirla con otras personas en la red. La grabación se puede guardar en un archivo local con el método showOpenFilePicker().

El siguiente ejemplo muestra cómo puedes grabar la pantalla del usuario en formato WebM, obtener una vista previa local en la misma página y guardar la grabación en el sistema de archivos del usuario.

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();
});

Navegadores compatibles

MediaDevices.getDisplayMedia()

Navegadores compatibles

  • 72
  • 79
  • 66
  • 13

Origen

API de MediaRecorder

Navegadores compatibles

  • 47
  • 79
  • 25
  • 14.1

Origen

API de showSaveFilePicker() de acceso al sistema de archivos

Navegadores compatibles

  • 86
  • 86
  • x
  • x

Origen

Lecturas adicionales

Demostración

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link
      rel="icon"
      href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🖥️</text></svg>"
    />
    <title>How to record the user's screen</title>
  </head>
  <body>
    <h1>How to record the user's screen</h1>
    <button id="startShareScreenButton">Start sharing screen</button>
    <button id="stopShareScreenButton" disabled>Stop sharing screen</button>
    <button id="startRecordButton" disabled>Start recording</button>
    <button id="stopRecordButton" disabled>Stop recording</button>
    <video autoplay muted playsinline></video>
    <pre id="logs"></pre>
  </body>
</html>

CSS


        :root {
  color-scheme: dark light;
}
html {
  box-sizing: border-box;
}
*,
*:before,
*:after {
  box-sizing: inherit;
}
body {
  margin: 1rem;
  font-family: system-ui, sans-serif;
}
button {
  display: block;
  margin-bottom: 4px;
}
video {
  display: block;
  margin-top: 10px;
  max-width: 100%;
  background: black;
  max-height: 480px;
}
pre {
  color: red;
  white-space: pre-line;
}

JS


        const video = document.querySelector('video');
const startShareScreenButton = document.querySelector('#startShareScreenButton');
const stopShareScreenButton = document.querySelector('#stopShareScreenButton');
const startRecordButton = document.querySelector('#startRecordButton');
const stopRecordButton = document.querySelector('#stopRecordButton');

let stream;
let recorder;

startShareScreenButton.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;

  startRecordButton.disabled = false;
  stopShareScreenButton.disabled = false;
  log("Your screen is being shared.");
});

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

  stopShareScreenButton.disabled = true;
  startRecordButton.disabled = true;
  stopRecordButton.disabled = true;
  log("Your screen is not shared anymore.");
});

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.disabled = false;
  log("Your screen is being recorded locally.");
});

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

  stopRecordButton.disabled = true;
  log("Your screen has been successfully recorded locally.");
});