> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rebellapp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# my.onBluetoothAdapterStateChange

> Listen for Bluetooth adapter state changes.

Use this API to listen for changes in the Bluetooth adapter state, such as when Bluetooth is turned on or off.

## Parameters

| Property | Type     | Required | Description                         |
| -------- | -------- | -------- | ----------------------------------- |
| callback | Function | Yes      | Callback when adapter state changes |

## Callback Parameters

| Property    | Type    | Description                           |
| ----------- | ------- | ------------------------------------- |
| available   | Boolean | Whether Bluetooth is available        |
| discovering | Boolean | Whether currently discovering devices |

## Code Example

### Basic Usage

```javascript theme={null}
my.onBluetoothAdapterStateChange((res) => {
  console.log('Bluetooth available:', res.available);
  console.log('Discovering:', res.discovering);
});
```

### Handle Bluetooth Toggle

```javascript theme={null}
Page({
  onLoad() {
    my.onBluetoothAdapterStateChange(this.handleStateChange);
    my.openBluetoothAdapter();
  },

  handleStateChange(res) {
    if (!res.available) {
      my.alert({
        title: 'Bluetooth Disabled',
        content: 'Please enable Bluetooth to continue using this feature.'
      });
      this.setData({ bluetoothEnabled: false });
    } else {
      this.setData({ bluetoothEnabled: true });
    }
  },

  onUnload() {
    my.offBluetoothAdapterStateChange(this.handleStateChange);
    my.closeBluetoothAdapter();
  }
});
```

### Auto-Resume Discovery

```javascript theme={null}
Page({
  data: {
    shouldBeDiscovering: false
  },

  onLoad() {
    my.onBluetoothAdapterStateChange((res) => {
      if (res.available && this.data.shouldBeDiscovering && !res.discovering) {
        // Bluetooth came back, resume discovery
        my.startBluetoothDevicesDiscovery();
      }
    });
  },

  startScan() {
    this.setData({ shouldBeDiscovering: true });
    my.startBluetoothDevicesDiscovery();
  }
});
```

## Related APIs

<CardGroup cols={2}>
  <Card title="my.offBluetoothAdapterStateChange" icon="xmark" href="/jsapi/device/bluetooth/my.offBluetoothAdapterStateChange">
    Stop listening
  </Card>

  <Card title="my.getBluetoothAdapterState" icon="info" href="/jsapi/device/bluetooth/my.getBluetoothAdapterState">
    Get current state
  </Card>
</CardGroup>