The configuration read only property of the USBDevice interface returns a USBConfiguration object for the currently selected interface for a paired USB device.

A USBConfiguration object.

The following example uses this property to test for the existence of a USBConfiguration property to select a configuration before claiming an interface.

async function connectDevice(usbDevice) {
  await usbDevice.open();
  if (usbDevice.configuration === null) await usbDevice.selectConfiguration(1);
  await usbDevice.claimInterface(0);
}