# device.list

## Function

Returns the list of open devices still visible to the current program.

## Syntax

```bt
device.list()
```

## Parameters

No parameters.

## Return value

| Type | Description |
| ------ | ------ |
| Array | Returns an array of opened device information objects. |

## Device information field

Each object in the array represents an open device that is still visible to the current program.

| Field | Type | Must exist | Description |
| ------ | ------ | ------ | ------ |
| type | String | Yes | The device type, currently `serial`. |
| port | String | Yes | The serial port name used when opening the device. |
| baud_rate | Int | Yes | The baud rate used when opening the serial port. |
| closed | Bool | Yes | Whether the underlying device connection has been closed. `true` means it has been closed and cannot continue to read or write. |

## Example

```bt
// After opening a serial port, device.list() can show the device handles held by the current process.
port = device.open({type: 'serial', port: 'COM3'})
items = device.list()
result = items[0].closed

// Output: false
print result

port.close()
```

## Notes

- Weak references that have been released will be cleaned up when listing.
- `device.list()` only lists devices that have been opened in the current process and are still referenced, not a full serial port scan of the system.