files/en-us/web/api/vrpose/linearvelocity/index.md
{{APIRef("WebVR API")}}{{Deprecated_Header}}{{Non-standard_Header}}
The linearVelocity read-only property of the {{domxref("VRPose")}} interface returns an array representing the linear velocity vector of the {{domxref("VRDisplay")}} at the current timestamp, in meters per second.
[!NOTE] This property was part of the old WebVR API. It has been superseded by the WebXR Device API.
In other words, the current velocity at which the sensor is moving along the x, y, and z axes.
A {{jsxref("Float32Array")}}, or null if the VR sensor is not able to provide linear velocity data.
// rendering loop for a VR scene
function drawVRScene() {
// WebVR: Request the next frame of the animation
vrSceneFrame = vrDisplay.requestAnimationFrame(drawVRScene);
// Populate frameData with the data of the next frame to display
vrDisplay.getFrameData(frameData);
// Retrieve the linear velocity values for use in rendering
// curFramePose is a VRPose object
const curFramePose = frameData.pose;
const linVel = curFramePose.linearVelocity;
const lvx = linVel[0];
const lvy = linVel[1];
const lvz = linVel[2];
// render the scene
// …
// WebVR: submit the rendered frame to the VR display
vrDisplay.submitFrame();
}
This property was part of the old WebVR API that has been superseded by the WebXR Device API. It is no longer on track to becoming a standard.
Until all browsers have implemented the new WebXR APIs, it is recommended to rely on frameworks, like A-Frame, Babylon.js, or Three.js, or a polyfill, to develop WebXR applications that will work across all browsers. Read Meta's Porting from WebVR to WebXR guide for more information.
{{Compat}}