Screen Capture API

The Screen Capture API is relatively simple to use. Its sole method is MediaDevices.getDisplayMedia(), whose job is to ask the user to select a screen or portion of a screen to capture in the form of a MediaStream.

To start capturing video from the screen, you call getDisplayMedia() on navigator.mediaDevices:

captureStream =
  await navigator.mediaDevices.getDisplayMedia(displayMediaOptions);

The Promise returned by getDisplayMedia() resolves to a MediaStream which streams the captured media.

See the article Using the Screen Capture API for a more in-depth look at how to use the API to capture screen contents as a stream.

CaptureController

Provides methods that can be used to further manipulate a capture session separate from its initiation via MediaDevices.getDisplayMedia(). A CaptureController object is associated with a capture session by passing it into a getDisplayMedia() call as the value of the options object's controller property.

MediaDevices.getDisplayMedia()

The getDisplayMedia() method is added to the MediaDevices interface. Similar to getUserMedia(), this method creates a promise that resolves with a MediaStream containing the display area selected by the user, in a format that matches the specified options.

The Screen Capture API adds properties to the following dictionaries defined by other specifications.

MediaTrackConstraints.displaySurface

A ConstrainDOMString indicating what type of display surface is to be captured. The value is one of browser, monitor, or window.

MediaTrackConstraints.logicalSurface

Indicates whether or not the video in the stream represents a logical display surface (that is, one which may not be entirely visible onscreen, or may be completely offscreen). A value of true indicates a logical display surface is to be captured.

MediaTrackConstraints.suppressLocalAudioPlayback

Controls whether the audio playing in a tab will continue to be played out of a user's local speakers when the tab is captured, or whether it will be suppressed. A value of true indicates that it will be suppressed.

MediaTrackSettings.cursor

A string which indicates whether or not the display surface currently being captured includes the mouse cursor, and if so, whether it's only visible while the mouse is in motion or if it's always visible. The value is one of always, motion, or never.

MediaTrackSettings.displaySurface

A string indicating what type of display surface is currently being captured. The value is one of browser, monitor, or window.

MediaTrackSettings.logicalSurface

A boolean value, which is true if the video being captured doesn't directly correspond to a single onscreen display area.

MediaTrackSettings.suppressLocalAudioPlayback

A boolean value, which is true if the audio being captured is not played out of the user's local speakers.

MediaTrackSupportedConstraints.displaySurface

A boolean, which is true if the current environment supports the MediaTrackConstraints.displaySurface constraint.

MediaTrackSupportedConstraints.logicalSurface

A boolean, which is true if the current environment supports the constraint MediaTrackConstraints.logicalSurface.

MediaTrackSupportedConstraints.suppressLocalAudioPlayback

A boolean, which is true if the current environment supports the constraint MediaTrackConstraints.suppressLocalAudioPlayback.

User agents that support Permissions Policy (either using the HTTP Permissions-Policy header or the <iframe> attribute allow) can specify a desire to use the Screen Capture API using the directive display-capture:

<iframe allow="display-capture" src="/some-other-document.html">…</iframe>

The default allowlist is self, which lets any content within the same origin use Screen Capture.

• Using the Screen Capture API
• MediaDevices.getDisplayMedia()