voluptasmollitia/docs-exp/firestore_lite.documentid.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/firestore](./firestore.md) &gt; [lite](./firestore_lite.md) &gt; [documentId](./firestore_lite.documentid.md)

## documentId() function

Returns a special sentinel `FieldPath` to refer to the ID of a document. It can be used in queries to sort or filter by the document ID.

<b>Signature:</b>

```typescript
export declare function documentId(): FieldPath;
```
<b>Returns:</b>

[FieldPath](./firestore_lite.fieldpath.md)