VRLayerInit

// currently returns an empty array
let layers = vrDisplay.getLayers();

if (navigator.getVRDisplays) {
  console.log("WebVR 1.1 supported");
  // Then get the displays attached to the computer
  navigator.getVRDisplays().then((displays) => {
    // If a display is available, use it to present the scene
    if (displays.length > 0) {
      vrDisplay = displays[0];
      console.log("Display found");
      // Starting the presentation when the button is clicked: It can only be called in response to a user gesture
      btn.addEventListener("click", () => {
        vrDisplay.requestPresent([{ source: canvas }]).then(() => {
          console.log("Presenting to WebVR display");

          // Here it returns an array of VRLayerInit objects
          layers = vrDisplay.getLayers();

          // …
        });
      });
    }
  });
}

const init = {
  leftBounds: [
    /* … */
  ],
  rightBounds: [
    /* … */
  ],
  source: canvasReference,
};