# useSelection

Source: https://sdk.pdf.net/docs/v1/reference/useSelection



Returns what the user has selected: the paragraph being edited, or the ids of the selected blocks. Re-renders the component when the selection changes.

```ts
const selection = useSelection() // Selection | undefined
```

The value is a `Selection`:

| Value                          | Meaning                                                                                      |
| ------------------------------ | -------------------------------------------------------------------------------------------- |
| `{ type: 'text', blockId }`    | A paragraph is in text editing: the caret or a text range is inside the paragraph `blockId`. |
| `{ type: 'blocks', blockIds }` | Whole blocks are selected: paragraphs, annotations, or widgets.                              |
| `undefined`                    | Nothing is selected, or no document is loaded.                                               |

## Behavior [#behavior]

* Only the selection type and the ids are tracked. Moving the caret or changing the text range within the same paragraph, and editing a selected block, don't re-render the component; read the block content with [useSelectedBlocks](https://sdk.pdf.net/docs/v1/reference/useSelectedBlocks) instead.
* Deleted blocks are left out of `blockIds`. When none of the selected blocks exists, the value is `undefined`; if an undo restores them, they come back selected.
* The ids are session-scoped: don't store them across page reloads.

## Example [#example]

```tsx
import { useSelection } from '@sdk-pdf/react'

function SelectionToolbar() {
  const selection = useSelection()

  if (!selection) return null

  return (
    <div role="toolbar">
      {selection.type === 'text'
        ? 'Editing text'
        : `${selection.blockIds.length} selected`}
    </div>
  )
}
```

To change the selection, see [useSelectBlocks](https://sdk.pdf.net/docs/v1/reference/useSelectBlocks). To read it inside an event handler without subscribing, see [useSelectedBlocksGetter](https://sdk.pdf.net/docs/v1/reference/useSelectedBlocksGetter).