The getAvailability() method of the Bluetooth interface returns true if the device has a Bluetooth adapter, and false otherwise (unless the user has configured the browser to not expose a real value).

None.

A Promise that resolves with Boolean.

This method doesn't throw any exceptions.

The following snippet prints out a message in the console specifying whether or not Bluetooth is supported:

navigator.bluetooth.getAvailability().then((available) => {
  if (available) {
    console.log("This device supports Bluetooth!");
  } else {
    console.log("Doh! Bluetooth is not supported");
  }
});