BluetoothRemoteGATTServer: connected property
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
  The BluetoothRemoteGATTServer.connected read-only
  property returns a boolean value that returns true while this script execution
  environment is connected to this.device. It can be false while the user
  agent is physically connected.
Value
A boolean.
Specifications
| Specification | 
|---|
| Web Bluetooth  # dom-bluetoothremotegattserver-connected  | 
Browser compatibility
BCD tables only load in the browser