[Home](./index.md) > [@firebase/firestore](./firestore.md) > [/](./firestore_.md) > [setDoc](./firestore_.setdoc.md) ## setDoc() function Writes to the document referred to by this `DocumentReference`. If the document does not yet exist, it will be created. Signature: ```typescript export declare function setDoc(reference: DocumentReference, data: T): Promise; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | reference | [DocumentReference](./firestore_.documentreference.md)<T> | A reference to the document to write. | | data | T | A map of the fields and values for the document. | Returns: Promise<void> A Promise resolved once the data has been successfully written to the backend (note that it won't resolve while you're offline).