SerialPort: connected property

const ports = await navigator.serial.getPorts();
for (const port of ports) {
  if (port.connected) {
    // The port is logically connected
    // automatically try to reopen the port
    await port.open({ baudRate: 9600 });
  } else {
    // The port is not logically connected; at this point you could
    // prompt the user to make sure the Bluetooth device is available, and
    // Show a "connect" button to allow them to try opening the port if desired
  }
}

requestPortButton.addEventListener("click", async () => {
  const port = await navigator.serial.requestPort();
  console.log(`Requested serial port. Connected: ${port.connected}`);
});

navigator.serial.addEventListener("connect", ({ target: port }) => {
  console.log(`Connect event fired. Connected: ${port.connected}`);
});

navigator.serial.addEventListener("disconnect", ({ target: port }) => {
  console.log(`Disconnect event fired. Connected: ${port.connected}`);
});