DeviceOrientationEvent

DeviceOrientationEvent is a browser event used to report the physical orientation of a device relative to the Earth's coordinate frame. It is part of the Device Orientation API and is typically delivered to a page via event listeners on the window object. Applications include motion-based controls, augmented reality, navigation, and games that respond to how the device is tilted or rotated.

The event exposes several properties. Alpha represents rotation around the z-axis and ranges from 0 to 360 degrees. Beta represents rotation around the x-axis and ranges from -180 to 180 degrees. Gamma represents rotation around the y-axis and ranges from -90 to 90 degrees. The absolute property is a boolean that indicates whether the orientation is reported relative to the Earth’s coordinate frame (true) or a device-relative frame (false). Note that values may be null on devices or browsers that do not support the sensor or have permissions disabled.

Usage typically involves adding a listener, such as window.addEventListener('deviceorientation', handler), where the handler receives an event with the alpha, beta, gamma, and absolute properties. In some platforms, especially newer mobile browsers, access to orientation data may require explicit user permission or a user gesture before events begin firing.

Support and considerations vary by platform and permissions. The API is more commonly available on mobile devices and tablets, while desktop support is limited. Developers should handle null values and consider privacy implications when requesting access to orientation data.