@firebolt-js/openrpc/languages/markdown/templates/methods/once.md

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### once

To listen to a single instance of a specific event pass the event name as the first parameter:

```typescript
once(event: string, callback: (data: any) => void): Promise<number>
```

The `once` method will only pass the next instance of this event, and then dicard the listener you provided.

Parameters:

| Param                  | Type                 | Required                 | Summary                 |
| ---------------------- | -------------------- | ------------------------ | ----------------------- |
| `event` | `string` | Yes | The event to listen for, see [Events](#events). |
| *callback* | `function` | Yes | A function that will be invoked when the event occurs. |

Promise resolution:

| Type | Description |
|------|-------------|
| `number` | Listener ID to clear the callback method and stop receiving the event, e.g. `${info.title}.clear(id)` |

Callback parameters:

| Param                  | Type                 | Required                 | Summary                 |
| ---------------------- | -------------------- | ------------------------ | ----------------------- |
| `data` | `any` | Yes | The event data, which depends on which event is firing, see [Events](#events). |

To listen to the next instance only of any events from this module pass only a callback, without specifying an event name:

```typescript
once(callback: (event: string, data: any) => void): Promise<number>
```

Parameters:

| Param                  | Type                 | Required                 | Summary                 |
| ---------------------- | -------------------- | ------------------------ | ----------------------- |
| *callback* | `function` | Yes | A function that will be invoked when the event occurs. The event data depends on which event is firing, see [Events](#events). |


Callback parameters:

| Param                  | Type                 | Required                 | Summary                 |
| ---------------------- | -------------------- | ------------------------ | ----------------------- |
| `event` | `string` | Yes | The event that has occured listen for, see [Events](#events). |
| `data` | `any` | Yes | The event data, which depends on which event is firing, see [Events](#events). |


Promise resolution:

| Type | Description |
|------|-------------|
| `number` | Listener ID to clear the callback method and stop receiving the event, e.g. `${info.title}.clear(id)` |

See [Listening for events](../../docs/listening-for-events/) for more information and examples.