[Home](./index.md) > [@firebase/firestore](./firestore.md) > [/](./firestore_.md) > [WriteBatch](./firestore_.writebatch.md) > [update](./firestore_.writebatch.update.md) ## WriteBatch.update() method Updates fields in the document referred to by the provided [DocumentReference](./firestore_.documentreference.md). The update will fail if applied to a document that does not exist. Signature: ```typescript update(documentRef: DocumentReference, data: UpdateData): WriteBatch; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | documentRef | [DocumentReference](./firestore_.documentreference.md)<unknown> | A reference to the document to be updated. | | data | [UpdateData](./firestore_.updatedata.md) | An object containing the fields and values with which to update the document. Fields can contain dots to reference nested fields within the document. | Returns: [WriteBatch](./firestore_.writebatch.md) This `WriteBatch` instance. Used for chaining method calls.