demo · v131

all 26 joints, names + radii

A WebXR hand exposes 26 joints — wrist, four per finger (metacarpal, proximal, intermediate, distal), tip per finger. Each joint has a 3D pose and a radius for grasp detection. The list is the actual XRHand joint enumeration order; click a joint to highlight its position on the schematic.

session Real values require an immersive-vr or immersive-ar session on hardware that supports hand-tracking (Quest, AVP). On a desktop browser the schematic is illustrative — joint names and radii are the real spec values; positions are example data.
selected jointwrist radius— role—

    the api

    // In an XR animation frame
for (const inputSource of session.inputSources) {
  if (!inputSource.hand) continue;
  for (const [name, jointSpace] of inputSource.hand.entries()) {
    const pose = frame.getJointPose(jointSpace, refSpace);
    // pose.transform.position, pose.transform.orientation
    // pose.radius   - sphere of contact for the joint
  }
}

    see also