# PDFViewer.off()

```ts
off<K extends keyof ViewerEventMap>(event: K, handler: (data: ViewerEventMap[K]) => void): void
```

Unsubscribe from an event, with the same handler reference.

- Kind: method
- Since: 1.0.0

| Parameter | Type | Description |
| --- | --- | --- |
| `event` | `keyof ViewerEventMap` | The event name. |
| `handler` | `(data: ViewerEventMap[K]) => void` | The same handler reference that was passed to `on()`. |

Returns `void`

```ts
const onPage = (data: ViewerEventMap['pageChanged']) => setCurrentPage(data.pageIndex);
viewer.on('pageChanged', onPage);
viewer.off('pageChanged', onPage);
```

Part of [PDFViewer](https://kernstra.com/docs/web-sdk/api/pdfviewer) in the Kernstra Web SDK 1.0.0 API reference.

Web page: https://kernstra.com/docs/web-sdk/api/pdfviewer/off