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

# Observe Property

> Monitor changes to a specified property in the browser window object

The Observe Property command (Command Type: 12) monitors changes on a specified property in an object within the browser's `window` context. It overrides the getter/setter for the property to capture real-time updates.

## Command Type

**Command Type ID:** 12

## Parameters

| Parameter            | Type                                     | Description                                                      | Required |
| -------------------- | ---------------------------------------- | ---------------------------------------------------------------- | -------- |
| **key**              | string                                   | The name of the property to observe within the target object     | Yes      |
| **name**             | string                                   | A unique identifier for this listener                            | Yes      |
| **parentObjectPath** | string                                   | Dot-path to the parent object in the `window` context            | Yes      |
| **timeout**          | number                                   | Timeout in milliseconds                                          | Yes      |
| **correlationId**    | string                                   | Unique identifier to correlate events triggered by this observer | No       |
| **sendOnChange**     | Array of NamedGetWindowDataCommandParams | Additional data to send when the observed property changes       | No       |

## Usage Examples

### Observe a State Property

```json theme={null}
{
  "command": "observe-property",
  "params": {
    "key": "currentOdds",
    "name": "oddsObserver",
    "parentObjectPath": "app.state",
    "timeout": 60000
  }
}
```

### Observe with Additional Data Fetch

```json theme={null}
{
  "command": "observe-property",
  "params": {
    "key": "selectedEvent",
    "name": "eventObserver",
    "parentObjectPath": "window.store",
    "timeout": 30000,
    "sendOnChange": [
      {
        "name": "eventDetails",
        "timeout": 5000,
        "params": { "path": ["store", "eventDetails"], "timeout": 5000 }
      }
    ]
  }
}
```

## Related Commands

* [Get Window Data](/stream/commands/browser/get-window-data) - One-time window data extraction
* [Subscribe WebSocket Event](/stream/commands/browser/subscribe-websocket-event) - Monitor WebSocket messages