MediaDevices

The MediaDevices interface provides access to connected media input devices like cameras and microphones, as well as screen sharing. In essence, it lets you obtain access to any hardware source of media data.

Properties

Inherits properties from its parent EventTarget.

Event handlers

MediaDevices.ondevicechange

The event handler for the devicechange event. This event is delivered to the MediaDevices object when a media input or output device is attached to or removed from the user's computer.

Methods

Inherits methods from its parent EventTarget.

EventTarget.addEventListener()

Registers an event handler to a specific event type.

MediaDevices.enumerateDevices()

Obtains an array of information about the media input and output devices available on the system.

MediaDevices.getSupportedConstraints()

Returns an object conforming to MediaTrackSupportedConstraints indicating which constrainable properties are supported on the MediaStreamTrack interface. See Capabilities and constraints in Media Capture and Streams API (Media Streams) to learn more about constraints and how to use them.

MediaDevices.getUserMedia()

With the user's permission through a prompt, turns on a camera or screensharing and/or a microphone on the system and provides a MediaStream containing a video track and/or an audio track with the input.

EventTarget.removeEventListener()

Removes an event listener.

Example

'use strict';

// Put variables in global scope to make them available to the browser console.
var video = document.querySelector('video');
var constraints = window.constraints = {
  audio: false,
  video: true
};
var errorElement = document.querySelector('#errorMsg');

navigator.mediaDevices.getUserMedia(constraints)
.then(function(stream) {
  var videoTracks = stream.getVideoTracks();
  console.log('Got stream with constraints:', constraints);
  console.log('Using video device: ' + videoTracks[0].label);
  stream.onremovetrack = function() {
    console.log('Stream ended');
  };
  window.stream = stream; // make variable available to browser console
  video.srcObject = stream;
})
.catch(function(error) {
  if (error.name === 'ConstraintNotSatisfiedError') {
    errorMsg('The resolution ' + constraints.video.width.exact + 'x' +
        constraints.video.width.exact + ' px is not supported by your device.');
  } else if (error.name === 'PermissionDeniedError') {
    errorMsg('Permissions have not been granted to use your camera and ' +
      'microphone, you need to allow the page access to your devices in ' +
      'order for the demo to work.');
  }
  errorMsg('getUserMedia error: ' + error.name, error);
});

function errorMsg(msg, error) {
  errorElement.innerHTML += '<p>' + msg + '</p>';
  if (typeof error !== 'undefined') {
    console.error(error);
  }
}

Specifications

Browser compatibility

[1] Support for the devicechange event and for MediaDevices.ondevicechange landed in Firefox 51, but only for Mac, and disabled by default. It can be enabled by setting the preference media.ondevicechange.enabled to true. Support for this event was added for Linux and Windows—and it was enabled by default—starting in Firefox 52.

See also

• Media Capture and Streams API: The API this interface is part of.
• WebRTC API
• Navigator.mediaDevices: Returns a reference to a MediaDevices object that can be used to access devices.
• CameraCaptureJS: HTML5 video capture and playback using MediaDevices and the MediaStream Recording API (source on GitHub)
• OpenLang: HTML5 video language lab web application using MediaDevices and the MediaStream Recording API for video recording (source on GitHub)