The WebXR Device API's XRSession interface represents an ongoing XR session, providing methods and properties used to interact with and control the session. To open a WebXR session, use the XRSystem interface's requestSession() method.

With XRSession methods, you can poll the viewer's position and orientation (the XRViewerPose), gather information about the user's environment, and present imagery to the user. XRSession supports both inline and immersive virtual and augmented reality modes.

In addition to the properties listed below, XRSession inherits properties from its parent interface, EventTarget.

depthDataFormat Experimental Read only

Returns the depth-sensing data format with which the session was configured.

depthUsage Experimental Read only

Returns the depth-sensing usage with which the session was configured.

domOverlayState Experimental Read only

Provides information about the DOM overlay, if the feature is enabled.

environmentBlendMode Experimental Read only

Returns this session's blend mode which denotes how much of the real-world environment is visible through the XR device and how the device will blend the device imagery with it.

inputSources Experimental Read only

Returns a list of this session's XRInputSources, each representing an input device used to control the camera and/or scene.

interactionMode Experimental Read only

Returns this session's interaction mode, which describes the best space (according to the user agent) for the application to draw interactive UI for the current session.

preferredReflectionFormat Experimental Read only

Returns this session's preferred reflection format used for lighting estimation texture data.

renderState Experimental Read only

An XRRenderState object which contains options affecting how the imagery is rendered. This includes things such as the near and far clipping planes (distances defining how close and how far away objects can be and still get rendered), as well as field of view information.

visibilityState Experimental Read only

A string indicating whether or not the session's imagery is visible to the user, and if so, if it's being visible but not currently the target for user events.

XRSession provides the following methods in addition to those inherited from its parent interface, EventTarget.

cancelAnimationFrame() Experimental

Removes a callback from the animation frame painting callback from XRSession's set of animation frame rendering callbacks, given the identifying handle returned by a previous call to requestAnimationFrame().

end() Experimental

Ends the WebXR session. Returns a promise which resolves when the session has been shut down.

requestAnimationFrame() Experimental

Schedules the specified method to be called the next time the user agent is working on rendering an animation frame for the WebXR device. Returns an integer value which can be used to identify the request for the purposes of canceling the callback using cancelAnimationFrame(). This method is comparable to the Window.requestAnimationFrame() method.

requestHitTestSource() Experimental

Requests an XRHitTestSource object that handles hit test subscription.

requestHitTestSourceForTransientInput() Experimental

Requests an XRTransientInputHitTestSource object that handles hit test subscription for a transient input source.

requestLightProbe() Experimental

Requests an XRLightProbe that estimates lighting information at a given point in the user's environment.

requestReferenceSpace() Experimental

Requests that a new XRReferenceSpace of the specified type be created. Returns a promise which resolves with the XRReferenceSpace or XRBoundedReferenceSpace which was requested, or throws a NotSupportedError DOMException if the requested space type isn't supported by the device.

updateRenderState() Experimental

Updates the properties of the session's render state.

The following events are delivered to XRSession objects.

end Experimental

Sent to the XRSession object after the WebXR session has ended and all hardware-related functions have completed. The event is represented by an object of type XRSessionEvent. Also available through the onend event handler property.

inputsourceschange Experimental

An event of type XRInputSourcesChangeEvent sent to the XRSession when the list of active XR input sources has changed. Also available through the oninputsourceschange event handler property.

select Experimental

An event of type XRInputSourceEvent which is sent to the session when one of the session's input sources has successfully completed a primary action. This generally corresponds to the user pressing a trigger, touchpad, or button, speaks a command, or performs a recognizable gesture. The select event is sent after the selectstart event is sent and immediately before the selectend event is sent. If select is not sent, then the select action was aborted before being completed. Also available through the onselect event handler property.

selectend Experimental

An event of type XRInputSourceEvent which gets sent to the session object when one of its input devices finishes its primary action or gets disconnected while in the process of handling a primary action. For example: for button or trigger actions, this means the button has been released; for spoken commands, it means the user has finished speaking. This is the last of the three select* events to be sent. Also available through the onselectend event handler property.

selectstart Experimental

An event of type XRInputSourceEvent which is sent to the session object when one of its input devices is first engaged by the user in such a way as to cause the primary action to begin. This is the first of the session* event to be sent. Also available through the onselectstart event handler property.

squeeze Experimental

An XRInputSourceEvent sent to indicate that a primary squeeze action has successfully completed. This indicates that the device being squeezed has been released, and may represent dropping a grabbed object, for example. It is sent immediately before the squeezeend event is sent to indicate that the squeeze action is over. Also available through the onsqueeze event handler property.

squeezeend Experimental

An XRInputSourceEvent sent to the XRSession when the primary squeeze action ends, whether or not the action was successful. Also available using the onsqueezeend event handler property.

squeezestart Experimental

An event of type XRInputSourceEvent which is sent to the XRSession when the user initially squeezes a squeezable controller. This may be, for example, a trigger which is used to represent grabbing objects, or might represent actual squeezing when wearing a haptic glove. Also available through the onsqueezestart event handler property.

visibilitychange Experimental

An XRSessionEvent which is sent to the session when its visibility state as indicated by the visibilityState changes. Also available through the onvisibilitychange event handler property.

This example establishes a new XRSession in inline mode so that it can be displayed within an HTML element, avoiding the need for a dedicated AR or VR viewing device such as a headset.

const XR = navigator.xr;

if (XR) {
  XR.requestSession("inline").then((xrSession) => {
    xrSession.requestReferenceSpace("local").then((xrReferenceSpace) => {
      xrSession.requestAnimationFrame((time, xrFrame) => {
        const viewer = xrFrame.getViewerPose(xrReferenceSpace);

        gl.bindFramebuffer(xrWebGLLayer.framebuffer);

        for (const xrView of viewer.views) {
          const xrViewport = xrWebGLLayer.getViewport(xrView);
          gl.viewport(
            xrViewport.x,
            xrViewport.y,
            xrViewport.width,
            xrViewport.height,
          );
        }
      });
    });
  });
} else {
  /* WebXR is not available */
}