Secure context

This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The XRPermissionDescriptor dictionary's requiredFeatures property should be set prior to calling navigator.permissions.query() to a list of WebXR features which must be supported for the app to work. This ensures that permissions are checked as applicable to ensure that those features are available upon request.


xrPermissionDescriptor = {
   mode: xrSessionMode,
   requiredFeatures: reqFeatureList,
   optionalFeatures: optFeatureList

xrPermissionDescriptor.requiredFeatures = reqFeatureList;
reqFeatureList = xrPermissionDescriptor.requiredFeatures;


An array of strings indicating the WebXR features which must be available for use by the app or site. The permissions check will be performed in such a manner as to verify that all features in the list are available for use with the user's permission.

Currently, all features are members of the XRReferenceSpaceType enumerated type, indicating the reference space types that your app would like permission to use, but can operate without. Future editions of WebXR may add more recognized features.

The permitted values are:

The types of reference space are listed in the table below, with brief information about their use cases and which interface is used to implement them.

XRReferenceSpaceType Description Interface
bounded-floor Similar to the local type, except the user is not expected to move outside a predetermined boundary, given by the boundsGeometry in the returned object. XRBoundedReferenceSpace

A tracking space whose native origin is located near the viewer's position at the time the session was created. The exact position depends on the underlying platform and implementation. The user isn't expected to move much if at all beyond their starting position, and tracking is optimized for this use case.

For devices with six degrees of freedom (6DoF) tracking, the local reference space tries to keep the origin stable relative to the environment.

local-floor Similar to the local type, except the starting position is placed in a safe location for the viewer to stand, where the value of the y axis is 0 at floor level. If that floor level isn't known, the user agent will estimate the floor level. If the estimated floor level is non-zero, the browser is expected to round it such a way as to avoid fingerprinting (likely to the nearest centimeter). XRReferenceSpace
unbounded A tracking space which allows the user total freedom of movement, possibly over extremely long distances from their origin point. The viewer isn't tracked at all; tracking is optimized for stability around the user's current position, so the native origin may drift as needed to accommodate that need. XRReferenceSpace
viewer A tracking space whose native origin tracks the viewer's position and orientation. This is used for environments in which the user can physically move around, and is supported by all instances of XRSession, both immersive and inline, though it's most useful for inline sessions. It's particularly useful when determining the distance between the viewer and an input, or when working with offset spaces. Otherwise, typically, one of the other reference space types will be used more often. XRReferenceSpace

Usage notes


In this example, permissions are checked to ensure that the user has granted permission for the site or app to use immersive augmented reality mode with the local-floor reference space (presumably since the user is unlikely to start to fly).

let xrPermissionDesc = {
  name: "xr",
  mode: "immersive-ar",
  requiredFeatures: [ "local-floor" ]

if (navigator.permissions) {
  navigator.permissions.query(xrPermissionDesc).then(({state}) => {
    switch(state) {
      case "granted":
      case "prompt":
        /* do nothing otherwise */
  .catch(err) {
} else {


Specification Status Comment
WebXR Device API
The definition of 'XRPermissionDescriptor.requiredFeatures' in that specification.
Working Draft Initial definition.

Browser compatibility

BCD tables only load in the browser

See also