---
id: fast-element.subtreebehavioroptions.selector
title: SubtreeBehaviorOptions.selector property
hide_title: true
---
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[@microsoft/fast-element](./fast-element.md) &gt; [SubtreeBehaviorOptions](./fast-element.subtreebehavioroptions.md) &gt; [selector](./fast-element.subtreebehavioroptions.selector.md)

## SubtreeBehaviorOptions.selector property

When subtrees are observed, a query selector is required to indicate which of potentially many nodes should be assigned to the property.

<b>Signature:</b>

```typescript
selector: string;
```