XRSession: visibilitychange event

The visibilitychange event is sent to an {{domxref("XRSession")}} to inform it when it becomes visible or hidden, or when it becomes visible but not currently focused. Upon receiving the event, you can check the value of the session's {{domxref("XRSession.visibilityState", "visibilityState")}} property to determine the new visibility state.

Syntax

Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}}, or set an event handler property.

js-nolint

addEventListener("visibilitychange", (event) => { })

onvisibilitychange = (event) => { }

Event type

An {{domxref("XRSessionEvent")}}. Inherits from {{domxref("Event")}}.

Event properties

In addition to the properties listed below, properties from the parent interface, {{domxref("Event")}}, are available.

{{domxref("XRSessionEvent.session", "session")}} {{ReadOnlyInline}}
- : The {{domxref("XRSession")}} to which the event refers.

Description

Trigger

Triggered when an {{domxref("XRSession")}} becomes visible or hidden, or when it becomes visible but not currently focused.

When the XRSession receives this event, the visibility state has already been changed.

Use cases

Upon receiving the event, you can check the value of the session's {{domxref("XRSession.visibilityState", "visibilityState")}} property to determine the new visibility state.

Examples

This example demonstrates how to listen for a visibilitychange event on a WebXR session, using {{domxref("EventTarget.addEventListener", "addEventListener()")}} to begin listening for the event:

navigator.xr.requestSession("inline").then((xrSession) => {
  xrSession.addEventListener("visibilitychange", (e) => {
    switch (e.session.visibilityState) {
      case "visible":
      case "visible-blurred":
        mySessionVisible(true);
        break;
      case "hidden":
        mySessionVisible(false);
        break;
    }
  });
});

When a visibility state change occurs, the event is received and dispatched to a function mySessionVisible(), with a Boolean parameter indicating whether or not the session is presently being displayed to the user.

You can also create the event handler by assigning it to the {{domxref("XRSession")}}'s onvisibilitychange event handler property, like this:

xrSession.onvisibilitychange = (e) => {
  /* event handled here */
};