This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The reason read-only property of the VRDisplayEvent interface returns a human-readable reason why the event was fired.


var myReason = vrDisplayEventInstance.reason;


A string representing the reason why the event was fired. The available reasons are defined in the VRDisplayEventReason enum, and are as follows:

  • mounted — The VRDisplay has detected that the user has put it on (or it has been otherwise activated).
  • navigation — The page has been navigated to from a context that allows this page to begin presenting immediately, such as from another site that was already in VR presentation mode.
  • requested — The user agent has requested that VR presentation mode be started. This allows user agents to include a consistent UI to enter VR across diferent sites.
  • unmounted — The VRDisplay has detected that the user has taken it off (or it has been otherwise slept/put on standby).


window.addEventListener('vrdisplaypresentchange', function(e) {
  console.log('Display ' + e.display.displayId + ' presentation has changed. Reason given: ' + e.reason + '.');


Specification Status Comment
WebVR 1.1
The definition of 'reason' in that specification.
Draft Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support No15



No ? ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support No561 2 3 4 ? ? ? ?6.0

1. Only works in an experimental version of Chrome. (Other builds won't return any devices when Navigator.getVRDisplays() is invoked.)

2. Daydream View supported in Chrome 56.

3. Google Cardboard supported in Chrome 57.

4. From version 56: this feature is behind the WebVR preference. To change preferences in Chrome, visit chrome://flags.

5. Windows support was enabled in Firefox 55.

6. macOS support was enabled in Firefox 63.

See also

Document Tags and Contributors

Contributors to this page: fscholz, chrisdavidmills
Last updated by: fscholz,