The opened read-only property of the HIDDevice interface returns true if the connection to the HIDDevice is open and ready to transfer data.

A boolean value, true if the connection is open.

The following example retrieves devices with HID.getDevices() and logs the value of opened to the console.

document.addEventListener("DOMContentLoaded", async () => {
  let devices = await navigator.hid.getDevices();
  devices.forEach((device) => {
    console.log(`HID: ${device.opened}`);
  });
});